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Vaccines for International Travel

  • David O. Freedman
    Correspondence
    Correspondence: Address to David O. Freedman, MD, Division of Infectious Diseases, University of Alabama at Birmingham, 1720 2nd Ave S, BBRB #203, Birmingham, AL 35294-2170.
    Affiliations
    Division of Infectious Diseases, William C. Gorgas Center for Geographic Medicine, University of Alabama at Birmingham
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  • Lin H. Chen
    Affiliations
    Division of Infectious Diseases and Travel Medicine, Mount Auburn Hospital, Cambridge, MA

    Department of Medicine, Harvard Medical School, Boston, MA
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      Abstract

      The pretravel management of the international traveler should be based on risk management principles. Prevention strategies and medical interventions should be based on the itinerary, preexisting health factors, and behaviors that are unique to the traveler. A structured approach to the patient interaction provides a general framework for an efficient consultation. Vaccine-preventable diseases play an important role in travel-related illnesses, and their impact is not restricted to exotic diseases in developing countries. Therefore, an immunization encounter before travel is an ideal time to update all age-appropriate immunizations as well as providing protection against diseases that pose additional risk to travelers that may be delineated by their destinations or activities. This review focuses on indications for each travel-related vaccine together with a structured synthesis and graphics that show the geographic distribution of major travel-related diseases and highlight particularly high-risk destinations and behaviors. Dosing, route of administration, need for boosters, and possible accelerated regimens for vaccines administered prior to travel are presented. Different underlying illnesses and medications produce different levels of immunocompromise, and there is much unknown in this discipline. Recommendations regarding vaccination of immunocompromised travelers have less of an evidence base than for other categories of travelers. The review presents a structured synthesis of issues pertinent to considerations for 5 special populations of traveler: child traveler, pregnant traveler, severely immunocompromised traveler, HIV-infected traveler, and traveler with other chronic underlying disease including asplenia, diabetes, and chronic liver disease.

      Abbreviations and Acronyms:

      CDC (Centers for Disease Control and Prevention), HA (hepatitis A), HB (hepatitis B), IHR (International Health Regulations), MMR (measles, mumps, and rubella), VPA (vaccine-preventable disease), WHO (World Health Organization), YF (yellow fever)
      The pretravel management of the international traveler should be based on risk management principles. Prevention approaches and medical interventions should be individualized according to both the itinerary and factors such as behaviors that are dependent on the traveler. A structured approach to the patient interaction is the most efficient way to cover the necessary educational and preventive interventions.
      • Freedman D.O.
      • Chen L.H.
      • Kozarsky P.E.
      Medical considerations before international travel.
      Vaccine-preventable disease (VPD) in travelers is not restricted to exotic diseases in developing countries. For example, nonimmune adult US travelers are at significant risk of measles in wealthy industrialized countries including Western European countries and Mexico.
      • World Health Organization
      • Leong W.Y.
      Measles cases hit record high in Europe in 2018.
      In addition, imported measles and mumps have resulted in travel-related domestic outbreaks in the United States.
      • Bednarczyk R.A.
      • Rebolledo P.A.
      • Omer S.B.
      Assessment of the role of international travel and unauthorized immigration on measles importation to the United States.
      Figure 1 illustrates the large numbers of measles cases in developed countries in the 6 months ending August 2018 alone. Vaccine hesitancy is increasing in these countries as it is in the United States.
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      • Raude J.
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      • Verger P.
      Socioeconomic differences in childhood vaccination in developed countries: a systematic review of quantitative studies.
      Figure thumbnail gr1
      Figure 1Number of cases of measles reported to the World Health Organization for the 6 months ending August 2018; 23 countries including many in Europe reported more than 1000 cases during this period.
      The following sections, which focus on the main indications for each vaccine as used in the pretravel consultation, should be used in conjunction with the information in Figure 2
      • World Health Organization
      • Radhakrishnan A.
      • Als D.
      • Mintz E.D.
      • et al.
      Introductory article on global burden and epidemiology of typhoid fever.
      • Hills S.L.
      • Rabe I.B.
      • Fischer M.
      Japanese encephalitis.
      • Gershman M.D.
      • Staples J.E.
      Yellow fever.
      • MacNeil J.R.
      • Meyer S.A.
      Meningococcal disease.
      and Table 1,
      Centers for Disease Control and Prevention
      Travelers' Health. Vaccines. Medicines. Advice.
      • Fillion K.
      • Mileno M.D.
      Cholera in travelers: shifting tides in epidemiology, management, and prevention.
      • MacDonald E.
      • Steens A.
      • Stene-Johansen K.
      • et al.
      Increase in hepatitis A in tourists from Denmark, England, Germany, the Netherlands, Norway and Sweden returning from Egypt, November 2012 to March 2013.
      • Sane J.
      • de Sousa R.
      • van Pelt W.
      • Petrignani M.
      • Verhoef L.
      • Koopmans M.
      Risk of hepatitis A decreased among Dutch travelers to endemic regions in 2003 to 2011.
      • Chatziprodromidou I.P.
      • Bellou M.
      • Vantarakis G.
      • Vantarakis A.
      Viral outbreaks linked to fresh produce consumption: a systematic review.
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      • Torresi J.
      Hepatitis B and C infection in international travelers.
      • Dahl V.
      • Wallensten A.
      Self-reported infections during international travel and notifiable infections among returning international travellers, Sweden, 2009-2013.
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      • van Genderen P.
      • Ward B.J.
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      • Steffen R.
      • Osterhaus A.D.
      Travellers and influenza: risks and prevention.
      • Figueroa A.
      • Gulati R.K.
      • Rainey J.J.
      Estimating the frequency and characteristics of respiratory disease outbreaks at mass gatherings in the United States: findings from a state and local health department assessment.
      • Ma X.
      • Liu F.
      • Liu L.
      • et al.
      No MERS-CoV but positive influenza viruses in returning Hajj pilgrims, China, 2013-2015.
      • Wood S.
      • Telu K.
      • Tribble D.
      • et al.
      Infectious Disease Clinical Research Program TravMil Study Group
      Influenza-like illness in travelers to the developing world.
      • Huang G.K.L.
      • Tio S.Y.
      • Caly L.
      • et al.
      Prolonged detection of Japanese encephalitis virus in urine and whole blood in a returned short-term traveler.
      • Lindquist L.
      Recent and historical trends in the epidemiology of Japanese encephalitis and its implication for risk assessment in travellers.
      • Pearce J.C.
      • Learoyd T.P.
      • Langendorf B.J.
      • Logan J.G.
      Japanese encephalitis: the vectors, ecology and potential for expansion.
      • Heywood A.E.
      Measles: a re-emerging problem in migrants and travelers.
      • Smith-Palmer A.
      • Oates K.
      • Webster D.
      • et al.
      IMT
      Outbreak of Neisseria meningitidis capsular group W among scouts returning from the World Scout Jamboree, Japan, 2015.
      • Lucidarme J.
      • Scott K.J.
      • Ure R.
      • et al.
      An international invasive meningococcal disease outbreak due to a novel and rapidly expanding serogroup W strain, Scotland and Sweden, July to August 2015.
      Global Polio Eradication Initiative
      • Kashino W.
      • Piyaphanee W.
      • Kittitrakul C.
      • et al.
      Incidence of potential rabies exposure among Japanese expatriates and travelers in Thailand.
      • Gautret P.
      • Harvey K.
      • Pandey P.
      • et al.
      GeoSentinel Surveillance Network
      Animal-associated exposure to rabies virus among travelers, 1997-2012.
      • Shaw M.T.
      • Visser J.
      • Edwards C.
      Rabies postexposure consultations in New Zealand from 1998 to 2012.
      • Christiansen A.H.
      • Rodriguez A.B.
      • Nielsen J.
      • Cowan S.A.
      Should travellers to rabies-endemic countries be pre-exposure vaccinated? an assessment of post-exposure prophylaxis and pre-exposure prophylaxis given to Danes travelling to rabies-endemic countries 2000-12.
      • Bharti O.K.
      Human rabies in monkey (Macaca mulatta) bite patients a reality in India now!.
      • Depypere M.
      • Verhaegen J.
      • Derdelinckx I.
      • Meersseman W.
      A forgotten disease in a returning traveler from Thailand.
      • May M.L.
      • McDougall R.J.
      • Robson J.M.
      Corynebacterium diphtheriae and the returned tropical traveler.
      • Barbosa F.
      • Barnett E.D.
      • Gautret P.
      • et al.
      Bordetella pertussis infections in travelers: data from the GeoSentinel global network.
      • Steffen R.
      Epidemiology of tick-borne encephalitis (TBE) in international travellers to Western/Central Europe and conclusions on vaccination recommendations.
      • Gils S.
      • Frans J.
      • Ho E.
      • et al.
      Case report: tick-borne encephalitis (TBE) in a Belgian traveller returning from Germany.
      • Meltzer E.
      • Paran Y.
      • Lustig Y.
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      • Weinberger M.
      • Schwartz E.
      Travel-related tick-borne encephalitis, Israel, 2006-2014.
      • de Graaf J.A.
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      • Voorn G.P.
      • et al.
      First human case of tick-borne encephalitis virus infection acquired in the Netherlands, July 2016.
      • Kerlik J.
      • Avdičová M.
      • Štefkovičová M.
      • et al.
      Slovakia reports highest occurrence of alimentary tick-borne encephalitis in Europe: analysis of tick-borne encephalitis outbreaks in Slovakia during 2007-2016.
      • Farmakiotis D.
      • Varughese J.
      • Sue P.
      • et al.
      Typhoid fever in an inner city hospital: a 5-year retrospective review.
      • Hamer D.H.
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      • Caumes E.
      • et al.
      Fatal yellow fever in travelers to Brazil, 2018.
      • Wilder-Smith A.
      • Leong W.Y.
      Importation of yellow fever into China: assessing travel patterns.
      • Schönenberger S.
      • Hatz C.
      • Bühler S.
      Unpredictable checks of yellow fever vaccination certificates upon arrival in Tanzania.
      which show the geographic distribution of major travel-related diseases and highlight particularly high-risk destinations and behaviors. Table 2 includes dosing, route of administration, need for boosters, and possible accelerated regimens for vaccines administered before travel.
      Centers for Disease Control and Prevention
      ACIP vaccine recommendations and guidelines.
      • Wong K.K.
      • Burdette E.
      • Mahon B.E.
      • Mintz E.D.
      • Ryan E.T.
      • Reingold A.L.
      Recommendations of the Advisory Committee on Immunization Practices for use of cholera vaccine.
      • Hens N.
      • Habteab Ghebretinsae A.
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      • Van Damme P.
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      Long-term antibody persistence after vaccination with a 2-dose Havrix (inactivated hepatitis A vaccine): 20 years of observed data, and long-term model-based predictions.
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      • Folschweiller N.
      • Van Der Meeren O.
      Persistence of antibodies 20 y after vaccination with a combined hepatitis A and B vaccine.
      • Plumb I.D.
      • Bulkow L.R.
      • Bruce M.G.
      • et al.
      Persistence of antibody to hepatitis A virus 20 years after receipt of hepatitis A vaccine in Alaska.
      • Nelson N.P.
      • Link-Gelles R.
      • Hofmeister M.G.
      • et al.
      Update: recommendations of the Advisory Committee on Immunization Practices for use of hepatitis A vaccine for postexposure prophylaxis and for preexposure prophylaxis for international travel.
      • Leuridan E.
      • Van Damme P.
      Hepatitis B and the need for a booster dose.
      • Bruce M.G.
      • Bruden D.
      • Hurlburt D.
      • et al.
      Antibody levels and protection after hepatitis B vaccine: results of a 30-year follow-up study and response to a booster dose.
      • Jackson S.
      • Lentino J.
      • Kopp J.
      • et al.
      HBV-23 Study Group
      Immunogenicity of a two-dose investigational hepatitis B vaccine, HBsAg-1018, using a toll-like receptor 9 agonist adjuvant compared with a licensed hepatitis B vaccine in adults.
      • Schillie S.
      • Vellozzi C.
      • Reingold A.
      • et al.
      Prevention of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practices.
      • Grohskopf L.A.
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      • Fry A.M.
      • Jernigan D.B.
      Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices—United States, 2018-19 influenza season.
      Japanese encephalitis vaccines: WHO position paper – February 2015.
      • Paulke-Korinek M.
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      • Seidl-Friedrich C.
      • Jelinek T.
      Persistence of antibodies six years after booster vaccination with inactivated vaccine against Japanese encephalitis.
      • Cramer J.P.
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      • Paulke-Korinek M.
      • et al.
      One-year immunogenicity kinetics and safety of a purified chick embryo cell rabies vaccine and an inactivated Vero cell-derived Japanese encephalitis vaccine administered concomitantly according to a new, 1-week, accelerated primary series.
      • Cardemil C.V.
      • Dahl R.M.
      • James L.
      • et al.
      Effectiveness of a third dose of MMR vaccine for mumps outbreak control.
      • Marin M.
      • Marlow M.
      • Moore K.L.
      • Patel M.
      Recommendation of the Advisory Committee on Immunization Practices for use of a third dose of mumps virus-containing vaccine in persons at increased risk for mumps during an outbreak.
      • Baxter R.
      • Baine Y.
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      • Baccarini C.I.
      • Miller J.M.
      • Van der Wielen M.
      Five-year antibody persistence and booster response to a single dose of meningococcal A, C, W and Y tetanus toxoid conjugate vaccine in adolescents and young adults: an open, randomized trial.
      • Cohn A.C.
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      • Harrison L.H.
      • et al.
      Active Bacterial Core Surveillance (ABCs) Team and MeningNet Surveillance Partners
      Effectiveness and duration of protection of one dose of a meningococcal conjugate vaccine.
      Rabies vaccines: WHO position paper – April 2018.
      • Jonker E.F.F.
      • Visser L.G.
      Single visit rabies pre-exposure priming induces a robust anamnestic antibody response after simulated post-exposure vaccination: results of a dose-finding study.
      • Langedijk A.C.
      • De Pijper C.A.
      • Spijker R.
      • Holman R.
      • Grobusch M.P.
      • Stijnis C.
      Rabies antibody response after booster immunization: a systematic review and meta-analysis.
      • Chen L.H.
      • Gautret P.
      • Visser L.G.
      Rabies preexposure prophylaxis: application of updated World Health Organization position to travelers.
      • Soentjens P.
      • Andries P.
      • Aerssens A.
      • et al.
      Preexposure intradermal rabies vaccination: a noninferiority trial in healthy adults on shortening the vaccination schedule from 28 to 7 days.
      • Liang J.L.
      • Tiwari T.
      • Moro P.
      • et al.
      Prevention of pertussis, tetanus, and diphtheria with vaccines in the United States: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      World Health Organization. Vaccines against tick-borne encephalitis: WHO position paper.
      • World Health Organization
      Typhoid vaccines: WHO position paper, March 2018 - recommendations.
      Collaborative Group for Studies on Yellow Fever Vaccines
      Duration of post-vaccination immunity against yellow fever in adults.
      • Staples J.E.
      • Bocchini Jr., J.A.
      • Rubin L.
      • Fischer M.
      Yellow fever vaccine booster doses: recommendations of the Advisory Committee on Immunization Practices, 2015.
      • Lindsey N.P.
      • Horiuchi K.A.
      • Fulton C.
      • et al.
      Persistence of yellow fever virus-specific neutralizing antibodies after vaccination among US travellers.
      The Advisory Committee on Immunizations Practices provides comprehensive background and recommendations for administration of each individual vaccine
      Centers for Disease Control and Prevention
      ACIP vaccine recommendations and guidelines.
      ; unreferenced statements in this review can be assumed to reflect information found in these documents.
      Figure thumbnail gr2ab
      Figure 2Distribution of diseases preventable with travel vaccines. A, Hepatitis A. B, Typhoid fever. C, Japanese encephalitis. D, Tickborne encephalitis. E, Yellow fever, Africa. F, Yellow fever, Americas. G, Rabies. H, African meningitis belt.
      From the World Health Organization
      • World Health Organization
      (A); Am J Trop Med Hyg
      • Radhakrishnan A.
      • Als D.
      • Mintz E.D.
      • et al.
      Introductory article on global burden and epidemiology of typhoid fever.
      (B); the Centers for Disease Control and Prevention
      • Hills S.L.
      • Rabe I.B.
      • Fischer M.
      Japanese encephalitis.
      (C); the European Centre for Disease Prevention and Control (D); the Centers for Disease Control and Prevention
      • Gershman M.D.
      • Staples J.E.
      Yellow fever.
      (E and F); the World Health Organization (G); and the Centers for Disease Control and Prevention
      • MacNeil J.R.
      • Meyer S.A.
      Meningococcal disease.
      (H).
      Figure thumbnail gr2cd
      Figure 2Distribution of diseases preventable with travel vaccines. A, Hepatitis A. B, Typhoid fever. C, Japanese encephalitis. D, Tickborne encephalitis. E, Yellow fever, Africa. F, Yellow fever, Americas. G, Rabies. H, African meningitis belt.
      From the World Health Organization
      • World Health Organization
      (A); Am J Trop Med Hyg
      • Radhakrishnan A.
      • Als D.
      • Mintz E.D.
      • et al.
      Introductory article on global burden and epidemiology of typhoid fever.
      (B); the Centers for Disease Control and Prevention
      • Hills S.L.
      • Rabe I.B.
      • Fischer M.
      Japanese encephalitis.
      (C); the European Centre for Disease Prevention and Control (D); the Centers for Disease Control and Prevention
      • Gershman M.D.
      • Staples J.E.
      Yellow fever.
      (E and F); the World Health Organization (G); and the Centers for Disease Control and Prevention
      • MacNeil J.R.
      • Meyer S.A.
      Meningococcal disease.
      (H).
      Figure thumbnail gr2ef
      Figure 2Distribution of diseases preventable with travel vaccines. A, Hepatitis A. B, Typhoid fever. C, Japanese encephalitis. D, Tickborne encephalitis. E, Yellow fever, Africa. F, Yellow fever, Americas. G, Rabies. H, African meningitis belt.
      From the World Health Organization
      • World Health Organization
      (A); Am J Trop Med Hyg
      • Radhakrishnan A.
      • Als D.
      • Mintz E.D.
      • et al.
      Introductory article on global burden and epidemiology of typhoid fever.
      (B); the Centers for Disease Control and Prevention
      • Hills S.L.
      • Rabe I.B.
      • Fischer M.
      Japanese encephalitis.
      (C); the European Centre for Disease Prevention and Control (D); the Centers for Disease Control and Prevention
      • Gershman M.D.
      • Staples J.E.
      Yellow fever.
      (E and F); the World Health Organization (G); and the Centers for Disease Control and Prevention
      • MacNeil J.R.
      • Meyer S.A.
      Meningococcal disease.
      (H).
      Figure thumbnail gr2gh
      Figure 2Distribution of diseases preventable with travel vaccines. A, Hepatitis A. B, Typhoid fever. C, Japanese encephalitis. D, Tickborne encephalitis. E, Yellow fever, Africa. F, Yellow fever, Americas. G, Rabies. H, African meningitis belt.
      From the World Health Organization
      • World Health Organization
      (A); Am J Trop Med Hyg
      • Radhakrishnan A.
      • Als D.
      • Mintz E.D.
      • et al.
      Introductory article on global burden and epidemiology of typhoid fever.
      (B); the Centers for Disease Control and Prevention
      • Hills S.L.
      • Rabe I.B.
      • Fischer M.
      Japanese encephalitis.
      (C); the European Centre for Disease Prevention and Control (D); the Centers for Disease Control and Prevention
      • Gershman M.D.
      • Staples J.E.
      Yellow fever.
      (E and F); the World Health Organization (G); and the Centers for Disease Control and Prevention
      • MacNeil J.R.
      • Meyer S.A.
      Meningococcal disease.
      (H).
      Table 1Highlights of Vaccines for International Travel Noting Trip Characteristics Putting Travelers at Particularly High Risk and Examples of Recent Outbreaks With Implications for Travelers
      VaccineTrip characteristics suggesting particularly high riskRecent outbreaks or new findings with impact on travelersReferences
      Centers for Disease Control and Prevention
      Travelers' Health. Vaccines. Medicines. Advice.
      • Kerlik J.
      • Avdičová M.
      • Štefkovičová M.
      • et al.
      Slovakia reports highest occurrence of alimentary tick-borne encephalitis in Europe: analysis of tick-borne encephalitis outbreaks in Slovakia during 2007-2016.
      CholeraDestination with poor hygiene and sanitation where cholera is endemic; humanitarian aid work; some VFR travelersHaiti

      Somalia

      Yemen
      • Fillion K.
      • Mileno M.D.
      Cholera in travelers: shifting tides in epidemiology, management, and prevention.
      Hepatitis ADestinations with poor hygiene and sanitation practices; adventurous eating habits; men who have sex with menWidespread
      • MacDonald E.
      • Steens A.
      • Stene-Johansen K.
      • et al.
      Increase in hepatitis A in tourists from Denmark, England, Germany, the Netherlands, Norway and Sweden returning from Egypt, November 2012 to March 2013.
      ,
      • Sane J.
      • de Sousa R.
      • van Pelt W.
      • Petrignani M.
      • Verhoef L.
      • Koopmans M.
      Risk of hepatitis A decreased among Dutch travelers to endemic regions in 2003 to 2011.
      ,
      • Chatziprodromidou I.P.
      • Bellou M.
      • Vantarakis G.
      • Vantarakis A.
      Viral outbreaks linked to fresh produce consumption: a systematic review.
      Hepatitis BAdventure travel; medical tourism; health condition that may require medical intervention; injections or infusions; possibility of sexual contact at destinationNone
      • Johnson D.F.
      • Leder K.
      • Torresi J.
      Hepatitis B and C infection in international travelers.
      ,
      • Dahl V.
      • Wallensten A.
      Self-reported infections during international travel and notifiable infections among returning international travellers, Sweden, 2009-2013.
      Influenza (+ avian influenza)Mass gatherings; cruise ships; exposure to live poultrySaudi Arabia

      China

      Vietnam

      Indonesia
      • Goeijenbier M.
      • van Genderen P.
      • Ward B.J.
      • Wilder-Smith A.
      • Steffen R.
      • Osterhaus A.D.
      Travellers and influenza: risks and prevention.
      ,
      • Figueroa A.
      • Gulati R.K.
      • Rainey J.J.
      Estimating the frequency and characteristics of respiratory disease outbreaks at mass gatherings in the United States: findings from a state and local health department assessment.
      ,
      • Ma X.
      • Liu F.
      • Liu L.
      • et al.
      No MERS-CoV but positive influenza viruses in returning Hajj pilgrims, China, 2013-2015.
      ,
      • Wood S.
      • Telu K.
      • Tribble D.
      • et al.
      Infectious Disease Clinical Research Program TravMil Study Group
      Influenza-like illness in travelers to the developing world.
      Japanese encephalitisAdventure travel in agricultural areas; open-air accommodations; rural home stays; some VFR travelersBali

      China

      Thailand
      • Huang G.K.L.
      • Tio S.Y.
      • Caly L.
      • et al.
      Prolonged detection of Japanese encephalitis virus in urine and whole blood in a returned short-term traveler.
      ,
      • Lindquist L.
      Recent and historical trends in the epidemiology of Japanese encephalitis and its implication for risk assessment in travellers.
      ,
      • Pearce J.C.
      • Learoyd T.P.
      • Langendorf B.J.
      • Logan J.G.
      Japanese encephalitis: the vectors, ecology and potential for expansion.
      Measles, mumps, rubellaMass gatherings; travel to one of many areas with current outbreaks; travel to areas with antivaccine communityVenezuela, Brazil, Democratic Republic of the Congo

      Europe (England, France, Greece, Italy, Romania, Serbia, Ukraine)

      Indonesia

      Philippines
      • World Health Organization
      ,
      • Leong W.Y.
      Measles cases hit record high in Europe in 2018.
      ,
      • Bednarczyk R.A.
      • Rebolledo P.A.
      • Omer S.B.
      Assessment of the role of international travel and unauthorized immigration on measles importation to the United States.
      ,
      • Heywood A.E.
      Measles: a re-emerging problem in migrants and travelers.
      Meningococcal, quadrivalent ACYW-135Mass gatherings; sub-Saharan AfricaSaudi Arabia
      • Smith-Palmer A.
      • Oates K.
      • Webster D.
      • et al.
      IMT
      Outbreak of Neisseria meningitidis capsular group W among scouts returning from the World Scout Jamboree, Japan, 2015.
      ,
      • Lucidarme J.
      • Scott K.J.
      • Ure R.
      • et al.
      An international invasive meningococcal disease outbreak due to a novel and rapidly expanding serogroup W strain, Scotland and Sweden, July to August 2015.
      PoliovirusEndemic destinations with low vaccine coverage or disruption in health care infrastructure; humanitarian aid workAfghanistan, Nigeria, Pakistan

      Papua New Guinea

      Somalia, Democratic Republic of Congo
      Global Polio Eradication Initiative
      RabiesRemote destinations in areas with high incidence of canine rabies; behaviors with close contact with canines, wildlife, and batsIndonesia (Bali)

      Malaysia (Sarawak)

      India

      Thailand
      • Kashino W.
      • Piyaphanee W.
      • Kittitrakul C.
      • et al.
      Incidence of potential rabies exposure among Japanese expatriates and travelers in Thailand.
      ,
      • Gautret P.
      • Harvey K.
      • Pandey P.
      • et al.
      GeoSentinel Surveillance Network
      Animal-associated exposure to rabies virus among travelers, 1997-2012.
      ,
      • Shaw M.T.
      • Visser J.
      • Edwards C.
      Rabies postexposure consultations in New Zealand from 1998 to 2012.
      ,
      • Christiansen A.H.
      • Rodriguez A.B.
      • Nielsen J.
      • Cowan S.A.
      Should travellers to rabies-endemic countries be pre-exposure vaccinated? an assessment of post-exposure prophylaxis and pre-exposure prophylaxis given to Danes travelling to rabies-endemic countries 2000-12.
      ,
      • Bharti O.K.
      Human rabies in monkey (Macaca mulatta) bite patients a reality in India now!.
      Tetanus diphtheria pertussis (Tdap) or tetanus diphtheria (Td)Tetanus: participating in injury-prone activities such as cycling, riding motorcycle, construction

      Diphtheria: humanitarian aid, destinations with low vaccine coverage
      Diphtheria: Haiti, Venezuela, Bangladesh, Thailand, South Pacific, Vanuatu

      Pertussis: exposure occurs widely
      • Depypere M.
      • Verhaegen J.
      • Derdelinckx I.
      • Meersseman W.
      A forgotten disease in a returning traveler from Thailand.
      ,
      • May M.L.
      • McDougall R.J.
      • Robson J.M.
      Corynebacterium diphtheriae and the returned tropical traveler.
      ,
      • Barbosa F.
      • Barnett E.D.
      • Gautret P.
      • et al.
      Bordetella pertussis infections in travelers: data from the GeoSentinel global network.
      Tick-borne encephalitisHiking; camping; consuming unpasteurized dairy productsAustria, Czech Republic, Finland, Germany, Latvia, Norway, Sweden, Switzerland…
      • Steffen R.
      Epidemiology of tick-borne encephalitis (TBE) in international travellers to Western/Central Europe and conclusions on vaccination recommendations.
      ,
      • Gils S.
      • Frans J.
      • Ho E.
      • et al.
      Case report: tick-borne encephalitis (TBE) in a Belgian traveller returning from Germany.
      ,
      • Meltzer E.
      • Paran Y.
      • Lustig Y.
      • Stienlauf S.
      • Weinberger M.
      • Schwartz E.
      Travel-related tick-borne encephalitis, Israel, 2006-2014.
      ,
      • de Graaf J.A.
      • Reimerink J.H.
      • Voorn G.P.
      • et al.
      First human case of tick-borne encephalitis virus infection acquired in the Netherlands, July 2016.
      ,
      • Kerlik J.
      • Avdičová M.
      • Štefkovičová M.
      • et al.
      Slovakia reports highest occurrence of alimentary tick-borne encephalitis in Europe: analysis of tick-borne encephalitis outbreaks in Slovakia during 2007-2016.
      TyphoidDestinations with poor hygiene and sanitation practicesPakistan
      • Farmakiotis D.
      • Varughese J.
      • Sue P.
      • et al.
      Typhoid fever in an inner city hospital: a 5-year retrospective review.
      Yellow feverDestinations with known outbreaks or irregular requirementsBrazil: expanded risk areas to include Rio de Janeiro, Salvador, and Sao Paulo

      Angola, DRC, Nigeria
      • Hamer D.H.
      • Angelo K.
      • Caumes E.
      • et al.
      Fatal yellow fever in travelers to Brazil, 2018.
      ,
      • Wilder-Smith A.
      • Leong W.Y.
      Importation of yellow fever into China: assessing travel patterns.
      ,
      • Schönenberger S.
      • Hatz C.
      • Bühler S.
      Unpredictable checks of yellow fever vaccination certificates upon arrival in Tanzania.
      DRC = Democratic Republic of the Congo; VFR = visiting friends or relatives.
      Table 2Alphabetic VPD List With Dosing, Route, Schedule (Including Accelerated for Imminent Departures), and Duration of Protection
      ACIP = Advisory Committee on Immunization Practices; IM = intramuscular; NA = not applicable; SC = subcutaneous; US = United States; VPD = vaccine-preventable disease; WHO SAGE = World Health Organization Strategic Advisory Group of Experts.
      ,
      See respective ACIP recommendations48; only the most recent relevant ACIP publications are listed in the References column.
      VaccineVaccine type (specific type)Adult dosePediatric doseRouteStandard schedule of immunizationAccelerated schedule for seriesEstimated duration of protectionReference
      CholeraLive1 SachetNAOral1 DoseNA3-6 mo
      • Wong K.K.
      • Burdette E.
      • Mahon B.E.
      • Mintz E.D.
      • Ryan E.T.
      • Reingold A.L.
      Recommendations of the Advisory Committee on Immunization Practices for use of cholera vaccine.
      Hepatitis ANot live (inactivated virus)1 mLAge ≥12 mo: 0.5 mLIM2 Doses: days 0, 6-12 moTraveling children aged ≥6 mo should receive 1 dose pretravel and receive 2 doses of hepatitis A at age ≥12 mo

      Available in combined hepatitis A and B formulation: days 0, 7, 21 and 12 mo
      >25 y based on seropositivity; >40 y based on antibody modeling
      • Hens N.
      • Habteab Ghebretinsae A.
      • Hardt K.
      • Van Damme P.
      • Van Herck K.
      Model based estimates of long-term persistence of inactivated hepatitis A vaccine-induced antibodies in adults.
      ,
      • Theeten H.
      • Van Herck K.
      • Van Der Meeren O.
      • Crasta P.
      • Van Damme P.
      • Hens N.
      Long-term antibody persistence after vaccination with a 2-dose Havrix (inactivated hepatitis A vaccine): 20 years of observed data, and long-term model-based predictions.
      ,
      • Van Damme P.
      • Leroux-Roels G.
      • Suryakiran P.
      • Folschweiller N.
      • Van Der Meeren O.
      Persistence of antibodies 20 y after vaccination with a combined hepatitis A and B vaccine.
      ,
      • Plumb I.D.
      • Bulkow L.R.
      • Bruce M.G.
      • et al.
      Persistence of antibody to hepatitis A virus 20 years after receipt of hepatitis A vaccine in Alaska.
      ,
      • Nelson N.P.
      • Link-Gelles R.
      • Hofmeister M.G.
      • et al.
      Update: recommendations of the Advisory Committee on Immunization Practices for use of hepatitis A vaccine for postexposure prophylaxis and for preexposure prophylaxis for international travel.
      Hepatitis BNot live (recombinant hepatitis B surface antigen)1 mLFrom birth: 0.5 mLIM3 Doses: day 0, 1 mo, and 6 moVarious options including: (1) days 0, 7, 21 and 12 mo; (2) days 0, 1, 2 and 12 mo>30 y
      • Leuridan E.
      • Van Damme P.
      Hepatitis B and the need for a booster dose.
      ,
      • Bruce M.G.
      • Bruden D.
      • Hurlburt D.
      • et al.
      Antibody levels and protection after hepatitis B vaccine: results of a 30-year follow-up study and response to a booster dose.
      Hepatitis B-CpGNot live (recombinant hepatitis B with adjuvant)0.5 mLNAIM2 Doses: day 0, 1 moNANo data, but appears noninferior to standard hepatitis B vaccine
      • Jackson S.
      • Lentino J.
      • Kopp J.
      • et al.
      HBV-23 Study Group
      Immunogenicity of a two-dose investigational hepatitis B vaccine, HBsAg-1018, using a toll-like receptor 9 agonist adjuvant compared with a licensed hepatitis B vaccine in adults.
      ,
      • Schillie S.
      • Vellozzi C.
      • Reingold A.
      • et al.
      Prevention of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practices.
      Combined hepatitis A and BNot live (inactivated virus and recombinant viral antigen)1 mLNA in US (pediatric formulation licensed in Canada, Europe, and other countries)IM3 Doses: day 0, 1 mo, and 6 mo4 Doses: days 0, 7, 21 and 12 mo>20 y based on seropositivity and anamnestic response; >40 y based on mathematical modeling
      • Van Damme P.
      • Leroux-Roels G.
      • Suryakiran P.
      • Folschweiller N.
      • Van Der Meeren O.
      Persistence of antibodies 20 y after vaccination with a combined hepatitis A and B vaccine.
      InfluenzaNot live (inactivated virus, trivalent or quadrivalent)0.5 mLAge ≥6 mo but dose varies per product.

      Age 6-35 mo: 0.25 mL or 0.5 mL

      Age ≥36 mo: 0.5 mL
      IM1 Dose (children <8 y require 2 doses administered ≥4 wk apart with a first receipt of influenza vaccination)NA1 y
      • Grohskopf L.A.
      • Sokolow L.Z.
      • Broder K.R.
      • Walter E.B.
      • Fry A.M.
      • Jernigan D.B.
      Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices—United States, 2018-19 influenza season.
      Not live (inactivated high-dose trivalent)0.5 mL (age ≥65 y)NAIM1 DoseNA1 y
      Not live (inactivated virus, adjuvanted trivalent)0.5 mL (age ≥65 y)NAIM1 DoseNA1 y
      Live (attenuated virus, quadrivalent)0.2 mL (0.1 mL in each nostril for age 2-49 y)Age 2-49 y: 0.2 mL (0.1 mL in each nostril)Intranasal spray1 Dose (children <8 y require 2 doses administered ≥4 wk apart with a first receipt of influenza vaccination)NA1 y
      Not live (recombinant, trivalent)0.5 mL (age ≥18 y)NAIM1 DoseNA1 y
      Not live (cell culture–based inactivated virus, trivalent)0.5 mLAge ≥4 y: 0.5 mLIM1 DoseNA1 y
      Japanese encephalitis, tissue culture–derivedNot live (Vero cell–derived inactivated virus)0.5 mLAge ≥2 mo through 2 y: 0.25 mL

      Age ≥3 y: 0.5 mL
      IM2 Doses: days 0, and between 7-281-2 y (booster with third dose leads to seropositivity for ≥6 y)
      Japanese encephalitis vaccines: WHO position paper – February 2015.
      ,
      • Paulke-Korinek M.
      • Kollaritsch H.
      • Kundi M.
      • Zwazl I.
      • Seidl-Friedrich C.
      • Jelinek T.
      Persistence of antibodies six years after booster vaccination with inactivated vaccine against Japanese encephalitis.
      ,
      • Cramer J.P.
      • Jelinek T.
      • Paulke-Korinek M.
      • et al.
      One-year immunogenicity kinetics and safety of a purified chick embryo cell rabies vaccine and an inactivated Vero cell-derived Japanese encephalitis vaccine administered concomitantly according to a new, 1-week, accelerated primary series.
      Measles, mumps. rubellaLive (attenuated virus)0.5 mLAge ≥12 mo: 0.5 mLSC2 Doses: day 0, 4 wkTraveling children aged ≥6 mo who are not yet vaccinated should receive 1 dose pretravel and receive 2 doses at age ≥12 moLifelong after 2 doses (third dose may be recommended for contacts during mumps outbreaks)
      • Cardemil C.V.
      • Dahl R.M.
      • James L.
      • et al.
      Effectiveness of a third dose of MMR vaccine for mumps outbreak control.
      ,
      • Marin M.
      • Marlow M.
      • Moore K.L.
      • Patel M.
      Recommendation of the Advisory Committee on Immunization Practices for use of a third dose of mumps virus-containing vaccine in persons at increased risk for mumps during an outbreak.
      Meningococcal, quadrivalent ACYW-135Not live (bacterial polysaccharide, conjugated)0.5 mLAge ≥2 mo for MenACYW-CRM, ≥9 mo for MenACYW-D: 0.5 mLIM2 Doses in adolescents: age 11-12 y, then age 16-18 yNA5 y
      • Baxter R.
      • Baine Y.
      • Kolhe D.
      • Baccarini C.I.
      • Miller J.M.
      • Van der Wielen M.
      Five-year antibody persistence and booster response to a single dose of meningococcal A, C, W and Y tetanus toxoid conjugate vaccine in adolescents and young adults: an open, randomized trial.
      ,
      • Cohn A.C.
      • MacNeil J.R.
      • Harrison L.H.
      • et al.
      Active Bacterial Core Surveillance (ABCs) Team and MeningNet Surveillance Partners
      Effectiveness and duration of protection of one dose of a meningococcal conjugate vaccine.
      PoliovirusNot live (inactivated virus)0.5 mLAge ≥2 mo: 0.5 mLSC1 Dose in those with primary childhood seriesNALifelong, after primary series plus an adult (age ≥18 y) booster
      Centers for Disease Control and Prevention
      ACIP vaccine recommendations and guidelines.
      RabiesNot live (inactivated virus, human diploid cell)1 mLFrom birth: 1 mLIM3 Doses preexposure: days 0, 7 and 21 or 28Abbreviated course days 0, 7 dosing proposed by WHO SAGE, under evaluation by ACIP“Boostable” lifelong; 2 additional doses are required on days 0 and 3 after rabies exposure
      • Cramer J.P.
      • Jelinek T.
      • Paulke-Korinek M.
      • et al.
      One-year immunogenicity kinetics and safety of a purified chick embryo cell rabies vaccine and an inactivated Vero cell-derived Japanese encephalitis vaccine administered concomitantly according to a new, 1-week, accelerated primary series.
      ,
      Rabies vaccines: WHO position paper – April 2018.
      ,
      • Jonker E.F.F.
      • Visser L.G.
      Single visit rabies pre-exposure priming induces a robust anamnestic antibody response after simulated post-exposure vaccination: results of a dose-finding study.
      ,
      • Langedijk A.C.
      • De Pijper C.A.
      • Spijker R.
      • Holman R.
      • Grobusch M.P.
      • Stijnis C.
      Rabies antibody response after booster immunization: a systematic review and meta-analysis.
      ,
      • Chen L.H.
      • Gautret P.
      • Visser L.G.
      Rabies preexposure prophylaxis: application of updated World Health Organization position to travelers.
      ,
      • Soentjens P.
      • Andries P.
      • Aerssens A.
      • et al.
      Preexposure intradermal rabies vaccination: a noninferiority trial in healthy adults on shortening the vaccination schedule from 28 to 7 days.
      Not live (inactivated virus, purified chick embryo)1 mLFrom birth: 1 mLIM3 Doses preexposure: days 0, 7 and 21 or 28Abbreviated course days 0, 7 dosing proposed by WHO SAGE, under evaluation by ACIP“Boostable” lifelong; 2 additional doses are required on days 0 and 3 after rabies exposure
      • Cramer J.P.
      • Jelinek T.
      • Paulke-Korinek M.
      • et al.
      One-year immunogenicity kinetics and safety of a purified chick embryo cell rabies vaccine and an inactivated Vero cell-derived Japanese encephalitis vaccine administered concomitantly according to a new, 1-week, accelerated primary series.
      ,
      Rabies vaccines: WHO position paper – April 2018.
      ,
      • Jonker E.F.F.
      • Visser L.G.
      Single visit rabies pre-exposure priming induces a robust anamnestic antibody response after simulated post-exposure vaccination: results of a dose-finding study.
      ,
      • Langedijk A.C.
      • De Pijper C.A.
      • Spijker R.
      • Holman R.
      • Grobusch M.P.
      • Stijnis C.
      Rabies antibody response after booster immunization: a systematic review and meta-analysis.
      ,
      • Chen L.H.
      • Gautret P.
      • Visser L.G.
      Rabies preexposure prophylaxis: application of updated World Health Organization position to travelers.
      ,
      • Soentjens P.
      • Andries P.
      • Aerssens A.
      • et al.
      Preexposure intradermal rabies vaccination: a noninferiority trial in healthy adults on shortening the vaccination schedule from 28 to 7 days.
      Tetanus, diphtheria, pertussis (Tdap) or tetanus, diphtheria (Td)Not live (toxoid, protein antigen)0.5 mLAge ≥2 mo: 0.5 mLIM1 Dose in those with primary childhood series; boost with Tdap if no previous dose of TdapNA10 y
      • Liang J.L.
      • Tiwari T.
      • Moro P.
      • et al.
      Prevention of pertussis, tetanus, and diphtheria with vaccines in the United States: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      Tick-borne encephalitisNot live (inactivated virus)0.5 mLAge 3-16 y: 0.25 mL dose 1 followed by 0.5 mLIM3 Doses: day 0, 1-3 mo, and 5-12 mo3 Doses: days 0, 7, 213 y
      World Health Organization. Vaccines against tick-borne encephalitis: WHO position paper.
      TyphoidNot live (bacterial cell wall polysaccharide)0.5 mLAge ≥2 y: 0.5 mLIM1 DoseNA2 y
      • World Health Organization
      Typhoid vaccines: WHO position paper, March 2018 - recommendations.
      Live (attenuated bacteria)4 CapsulesAge ≥6 y: 4 capsulesOral4-Capsule series, 1 every other dayNA5 y
      Yellow feverLive (attenuated virus)0.5 mLAge ≥9 mo: 0.5 mLSC1 DoseNALifelong
      Collaborative Group for Studies on Yellow Fever Vaccines
      Duration of post-vaccination immunity against yellow fever in adults.
      ,
      • Staples J.E.
      • Bocchini Jr., J.A.
      • Rubin L.
      • Fischer M.
      Yellow fever vaccine booster doses: recommendations of the Advisory Committee on Immunization Practices, 2015.
      ,
      • Lindsey N.P.
      • Horiuchi K.A.
      • Fulton C.
      • et al.
      Persistence of yellow fever virus-specific neutralizing antibodies after vaccination among US travellers.
      a ACIP = Advisory Committee on Immunization Practices; IM = intramuscular; NA = not applicable; SC = subcutaneous; US = United States; VPD = vaccine-preventable disease; WHO SAGE = World Health Organization Strategic Advisory Group of Experts.
      b See respective ACIP recommendations
      Centers for Disease Control and Prevention
      ACIP vaccine recommendations and guidelines.
      ; only the most recent relevant ACIP publications are listed in the References column.

      Epidemiology of VPDs Related to Travel

      Influenza is the most common VPD of travelers, especially for those on cruise ships and those going to mass-gathering events such as the Hajj pilgrimage; risk is present at all destinations during transmission season at the destination.
      • Goeijenbier M.
      • van Genderen P.
      • Ward B.J.
      • Wilder-Smith A.
      • Steffen R.
      • Osterhaus A.D.
      Travellers and influenza: risks and prevention.
      • Figueroa A.
      • Gulati R.K.
      • Rainey J.J.
      Estimating the frequency and characteristics of respiratory disease outbreaks at mass gatherings in the United States: findings from a state and local health department assessment.
      • Ma X.
      • Liu F.
      • Liu L.
      • et al.
      No MERS-CoV but positive influenza viruses in returning Hajj pilgrims, China, 2013-2015.
      • Wood S.
      • Telu K.
      • Tribble D.
      • et al.
      Infectious Disease Clinical Research Program TravMil Study Group
      Influenza-like illness in travelers to the developing world.
      • Steffen R.
      Travel vaccine preventable diseases—updated logarithmic scale with monthly incidence rates.
      • Steffen R.
      • Behrens R.H.
      • Hill D.R.
      • Greenaway C.
      • Leder K.
      Vaccine-preventable travel health risks: what is the evidence—what are the gaps?.
      The rate of serologically confirmed influenza cases has been estimated at 8.9 per 100 person-months of travel.
      • Goeijenbier M.
      • van Genderen P.
      • Ward B.J.
      • Wilder-Smith A.
      • Steffen R.
      • Osterhaus A.D.
      Travellers and influenza: risks and prevention.
      • Steffen R.
      • Behrens R.H.
      • Hill D.R.
      • Greenaway C.
      • Leder K.
      Vaccine-preventable travel health risks: what is the evidence—what are the gaps?.
      For other VPDs, the risk for nonimmune travelers to developing countries is most significant for symptomatic hepatitis A (HA), at an estimated attack rate of 3.5 cases per 100,000 travelers to high or intermediate endemic regions.
      • Sane J.
      • de Sousa R.
      • van Pelt W.
      • Petrignani M.
      • Verhoef L.
      • Koopmans M.
      Risk of hepatitis A decreased among Dutch travelers to endemic regions in 2003 to 2011.
      • Steffen R.
      Travel vaccine preventable diseases—updated logarithmic scale with monthly incidence rates.
      The risk of symptomatic hepatitis B (HB) is most significant for long-stay travelers and expatriates, at 25 to 420 cases per 100,000 travelers.
      • Johnson D.F.
      • Leder K.
      • Torresi J.
      Hepatitis B and C infection in international travelers.
      Enteric fever (typhoid and paratyphoid) has a risk of 3 cases per 100,000 travelers per month on the Indian subcontinent and is 10 times lower in Africa and parts of Latin America.
      • Steffen R.
      Travel vaccine preventable diseases—updated logarithmic scale with monthly incidence rates.
      Among Swedish residents who traveled abroad, measles and pertussis incidence are estimated at about 3 cases per 100,000 travelers per month each. Risk of yellow fever (YF) may be high in an area with current epidemic transmission; at least 10 unvaccinated foreign travelers to Brazil acquired YF during a 2018 outbreak in Brazil. At the same time, the overall risk varies greatly between destinations encompassed by the endemic area map. The risk of meningococcal meningitis, rabies, cholera, polio, varicella, and Japanese encephalitis in travelers is not well characterized but is thought to be small even for travel to highly endemic areas.
      • Steffen R.
      Travel vaccine preventable diseases—updated logarithmic scale with monthly incidence rates.
      Travelers visiting friends and relatives in their country of origin are a group of travelers with especially high risk, particularly from malaria and typhoid; these travelers require special attention to illness prevention and education. The worldwide epidemiology of travel-related diseases is constantly changing. Online and print resources (Table 3) should be consulted frequently to keep current. Finally, additional considerations are required for special populations such as child travelers, pregnant travelers, immunocompromised travelers, HIV-infected travelers, and travelers with other underlying health conditions including asplenia, diabetes, and chronic liver disease (Table 4
      • Centers for Disease Control and Prevention (CDC)
      Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine for adults with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      • Centers for Disease Control and Prevention (CDC)
      Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine among children aged 6-18 years with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      • Finn T.M.
      • Egan W.
      Vaccine additives and manufacturing residuals in vaccines licensed in the United States.
      • Garcia Garrido H.M.
      • Wieten R.W.
      • Grobusch M.P.
      • Goorhuis A.
      Response to hepatitis A vaccination in immunocompromised travelers.
      • Hall V.
      • Johnson D.
      • Torresi J.
      Travel and biologic therapy: travel-related infection risk, vaccine response and recommendations.
      • Huber F.
      • Ehrensperger B.
      • Hatz C.
      • Chappuis F.
      • Bühler S.
      • Eperon G.
      Safety of live vaccines on immunosuppressive or immunomodulatory therapy—a retrospective study in three Swiss travel clinics.
      • Kobayashi M.
      • Bennett N.M.
      • Gierke R.
      • et al.
      Intervals between PCV13 and PPSV23 vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      • Kotton C.N.
      • Kroger A.T.
      • Freedman D.O.
      Immunocompromised travelers.
      • Kroger A.T.
      • Duchin J.
      • Vázquez M.
      General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP).
      • Lindsey N.P.
      • Rabe I.B.
      • Miller E.R.
      • Fischer M.
      • Staples J.E.
      Adverse event reports following yellow fever vaccination, 2007-13.
      • Rosdahl A.
      • Herzog C.
      • Frösner G.
      • Norén T.
      • Rombo L.
      • Askling H.H.
      An extra priming dose of hepatitis A vaccine to adult patients with rheumatoid arthritis and drug induced immunosuppression - a prospective, open-label, multi-center study.
      • Rubin L.G.
      • Levin M.J.
      • Ljungman P.
      • et al.
      2013 IDSA clinical practice guideline for vaccination of the immunocompromised host.
      • Tanizaki R.
      • Ujiie M.
      • Hori N.
      • et al.
      Comparative study of adverse events after yellow fever vaccination between elderly and non-elderly travellers: questionnaire survey in Japan over a 1-year period.
      • Trubiano J.A.
      • Johnson D.
      • Sohail A.
      • Torresi J.
      Travel vaccination recommendations and endemic infection risks in solid organ transplantation recipients.
      ).
      Table 3In-depth Information Resources for Travel Vaccines
      Authoritative websites updated constantly with epidemiological and outbreak information
       Centers for Disease Control and Prevention (CDC) Travelers Health
      Centers for Disease Control and Prevention
      Travelers' Health. Vaccines. Medicines. Advice.


      https://wwwnc.cdc.gov/travel
       World Health Organization (WHO) International Travel and Health

      https://www.who.int/ith/en/
       Public Health Agency of Canada. Committee to Advise on Tropical Medicine and Travel (CATMAT)

      https://www.canada.ca/en/public-health/services/catmat.html
       WHO Disease Outbreak News

      https://www.who.int/csr/don/en/
       WHO Weekly Epidemiological Record

      https://www.who.int/wer/en
       CDC Morbidity and Mortality Weekly Report

      https://www.cdc.gov/mmwr/index.html
      In-depth references on specialized topics
       Centers for Disease Control and Prevention. Health Information for International Travel 2020 (the “CDC Yellow Book”). New York, NY: Oxford University Press; 2020. Updated in even-numbered years. Full text and hard copy order information available at https://wwwnc.cdc.gov/travel/page/yellowbook-home
       World Health Organization. International Travel and Health (WHO “Green” Book). Full text online at https://www.who.int/ith/en/
       Centers for Disease Control and Prevention. Epidemiology and Prevention of Vaccine-Preventable Diseases (the “CDC Pink Book”). 13th ed. Washington, DC: Public Health Foundation; 2015. https://www.cdc.gov/vaccines/pubs/pinkbook/index.html
       Keystone JS, Kozarsky PE, Connor BA, Nothdurft HD, Mendelson M, Leder K, eds. Travel Medicine. 4th ed. Philadelphia, PA: Saunders; 2018. (ISBN: 9780323546966)
       Plotkin SA, Orenstein WA, Offit PA, Edwards KM. Plotkin's Vaccines. 7th ed. Philadelphia, PA: Elsevier; 2017. (ISBN: 9780323357616)
       Centers for Disease Control and Prevention. ACIP vaccine recommendations and guidelines.
      Centers for Disease Control and Prevention
      ACIP vaccine recommendations and guidelines.
      https://www.cdc.gov/vaccines/hcp/acip-recs/index.html
       Immunization Action Coalition. Food and Drug Administration: package inserts & FDA product approvals. http://www.immunize.org/fda/
       World Health Organization. Vaccine Position Papers. https://www.who.int/immunization/documents/positionpapers/en/
      Table 4Considerations for 5 Special Populations
      ACIP = Advisory Committee on Immunization Practices; C = child traveler; H = HIV-infected traveler; I = severely immunocompromised traveler; O = traveler with other chronic underlying disease including asplenia, diabetes, and chronic liver disease; P = pregnant traveler; PEP = postexposure prophylaxis.
      ,
      See references 80 through 93 in addition to those listed in Table 2.
      VaccineConsideration of contraindications/ precautions for special populationsAdditives/residuals/cell lines highlighting substances with potential sensitivity concerns
      Data from Plotkin's Vaccines82 and manufacturer's vaccine package inserts for cholera (Vaxchora; PaxVac, Inc), meningococcal conjugate (Menactra; Sanofi Pasteur Inc), pneumococcal conjugate (Prevnar; Pfizer Inc), pneumococcal polysaccharide (Pneumovax; Merck & Co, Inc), and tick-borne encephalitis (FSME-Immun; Pfizer Inc).
      Special indication beyond general ACIP recommendationsAttention to dosing recommendations for specific populations
      CholeraC: no data for <18 y

      P: vaccine strain may be shed in stool for ≥7 d, with a potential to transmit the vaccine strain to infant during vaginal delivery

      I: no data for immunocompromised individuals

      O: no contraindication for asplenia, despite this being a live vaccine
      Hydrolyzed casein, dried lactoseNoneNot applicable
      Hepatitis AP: no contraindication; may be used based on risk vs benefitAluminum, formalin, MRC-5 cells, nonviral proteins, neomycin sulfate, bovine albuminI: specifically recommended especially with transplant

      H: specifically recommended

      O: specifically recommended for liver disease, diabetes mellitus
      C: different pediatric dose (vs adult dose); administer noncountable dose at age 6-11 mo if travelling

      I: 1 dose provides suboptimal serologic response; administer ≥2 doses pretravel, consider second dose 1 mo after first dose for imminent travel or supplemental immunogloblulin

      O: chronic liver disease dose as per I
      Hepatitis BP: no contraindication; may be used if indicatedYeast protein, Saccharomyces cerevisiae cell lineI: specifically recommended especially with transplant

      H: specifically recommended

      O: specifically recommended for liver disease, diabetes mellitus, renal failure
      C: different pediatric dose (vs adult dose)

      O: use double-dose formulation for dialysis patients
      InfluenzaP: live-attenuated vaccine contraindicated; nonlive vaccines are recommended

      I: live-attenuated vaccine contraindicated; nonlive vaccines are recommended

      O: no contraindication for asplenia
      For inactivated quadrivalent or trivalent: β-propiolactone or formaldehyde in different formulations, thimerosal in multidose vialsCheck package insert because different cell lines used (embryonated chicken eggs, Madin-Darby Canine Kidney cells, Spodoptera frugiperda): +/- baculovirus and insect cell proteins and DNA, ovalbumin, neomycin, polymyxin B, non-HA protein, MDCK cell protein/DNA, polysorbate 80, gentamicin sulfateP: specifically recommended

      I: specifically recommended

      H: specifically recommended

      O: specifically recommended for all those with underlying chronic diseases
      C: children aged 6 mo through 8 y who are receiving their initial influenza vaccination should receive 2 doses >4 wk apart
      Japanese encephalitis, tissue culture–derivedP: no dataAluminum, formaldehyde, bovine serum albumin, Vero cells, host cell DNA, host cell proteinsNoneC: different pediatric dose for children <3 y
      Measles, mumps, rubellaP: contraindicated

      I: contraindicated

      H: contraindicated for CD4 cells <200

      O: no contraindication for asplenia, despite this being a live vaccine
      Hydrolyzed gelatin, chick embryo cell culture, WI-38 cells, recombinant human albumin, neomycin, bovine serum albuminC: specifically recommended for traveling children ≥6 mo who are not yet vaccinatedC: traveling children ≥6 mo should receive 1 dose pretravel, and receive 2 doses at ≥12 mo
      Meningococcal, quadrivalent ACYW-135, conjugatedP: no contraindication; may be used if indicatedDiphtheria toxoid protein, formaldehydeC: specifically recommended for age 2-23 mo if at increased risk (complement deficiency, asplenia, outbreak setting, travel)

      I: specifically recommended

      H: specifically recommended

      O: specifically recommended for asplenia or complement deficiency
      C: if at increased risk, administer either 4-dose series starting at 8 wk or 2-dose series depending on product and age at initial dose

      H: administer 2 doses 8-12 wk apart

      O: administer to persons with asplenia or complement deficiency every 5 y
      Pneumococcal, 13-valent conjugated (PCV13) and/or 23-valent polysaccharide (PPSV23)P: no dataPCV13: CRM197 carrier protein, aluminum phosphate adjuvant

      PPSV23: phenol
      I: Both PCV13 and PPSV23 are recommended for immunocompromised individuals

      H: specifically recommended

      O: specifically recommended for chronic liver disease, chronic lung disease, diabetes mellitus, cerebrospinal fluid leak, cochlear implant, sickle cell disease, asplenia, cigarette smoking
      I: PCV13 followed by PPSV23 with an interval of 8 wk; additional dose of PPSV23 recommended 5 y after initial dose for immunocompromised individuals

      O: PPSV23 only for chronic liver disease, chronic lung disease, diabetes mellitus, cerebrospinal fluid leak, cochlear implant, sickle cell disease, asplenia, cigarette smoking
      Poliovirus, inactivatedP: no contraindication; may be used if indicated2-Phenoxyethanol, formaldehyde, neomycin, streptomycin, polymyxin B, calf serum protein, Vero cellsNoneNone
      RabiesP: no contraindication; may be used if indicatedHuman diploid cell vaccine: MRC-5 cells, human serum albumin, neomycin chicken fibroblasts, ovalbumin, neomycin, chlortetracycline, amphotericin BNoneI: additional PEP dose recommended
      Tetanus, diphtheria, pertussis (Tdap) or tetanus, diphtheria (Td)P: no contraindicationAlum or aluminum, formaldehydeP: Tdap specifically recommended every pregnancyNone
      Tick-borne encephalitisP: precautionFSME-Immun: aluminum, human albuminNoneNone
      TyphoidP: live-attenuated vaccine contraindicated; may consider polysaccharide vaccine

      I: live-attenuated vaccine contraindicated; may administer polysaccharide vaccine
      Amino acid mixtureNoneNone
      Yellow feverC: contraindicated age <6 mo; precaution age 6-8 mo

      P: precaution; may be used based on risk vs benefit

      I: contraindicated

      H: contraindicated for uncontrolled viral load, CD4 cells <200, or those with AIDS-defining conditions

      O: no contraindication for asplenia, despite this being a live vaccine
      Gelatin, chicken embryoNoneC: additional dose recommended if vaccinated previously at age <5 y

      P: additional dose recommended if vaccinated previously during pregnancy

      I: additional dose recommended for those with prior yellow fever vaccination before hematopoietic stem cell transplant and who are at risk for yellow fever but are now immunocompetent

      H: additional dose recommended if vaccinated previously while HIV infected
      a ACIP = Advisory Committee on Immunization Practices; C = child traveler; H = HIV-infected traveler; I = severely immunocompromised traveler; O = traveler with other chronic underlying disease including asplenia, diabetes, and chronic liver disease; P = pregnant traveler; PEP = postexposure prophylaxis.
      b See references
      • Centers for Disease Control and Prevention (CDC)
      Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine for adults with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      through
      • Centers for Disease Control and Prevention (CDC)
      Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine among children aged 6-18 years with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      ,
      • Finn T.M.
      • Egan W.
      Vaccine additives and manufacturing residuals in vaccines licensed in the United States.
      ,
      • Garcia Garrido H.M.
      • Wieten R.W.
      • Grobusch M.P.
      • Goorhuis A.
      Response to hepatitis A vaccination in immunocompromised travelers.
      ,
      • Hall V.
      • Johnson D.
      • Torresi J.
      Travel and biologic therapy: travel-related infection risk, vaccine response and recommendations.
      ,
      • Huber F.
      • Ehrensperger B.
      • Hatz C.
      • Chappuis F.
      • Bühler S.
      • Eperon G.
      Safety of live vaccines on immunosuppressive or immunomodulatory therapy—a retrospective study in three Swiss travel clinics.
      ,
      • Kobayashi M.
      • Bennett N.M.
      • Gierke R.
      • et al.
      Intervals between PCV13 and PPSV23 vaccines: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      ,
      • Kotton C.N.
      • Kroger A.T.
      • Freedman D.O.
      Immunocompromised travelers.
      ,
      • Kroger A.T.
      • Duchin J.
      • Vázquez M.
      General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP).
      ,
      • Lindsey N.P.
      • Rabe I.B.
      • Miller E.R.
      • Fischer M.
      • Staples J.E.
      Adverse event reports following yellow fever vaccination, 2007-13.
      ,
      • Rosdahl A.
      • Herzog C.
      • Frösner G.
      • Norén T.
      • Rombo L.
      • Askling H.H.
      An extra priming dose of hepatitis A vaccine to adult patients with rheumatoid arthritis and drug induced immunosuppression - a prospective, open-label, multi-center study.
      ,
      • Rubin L.G.
      • Levin M.J.
      • Ljungman P.
      • et al.
      2013 IDSA clinical practice guideline for vaccination of the immunocompromised host.
      ,
      • Tanizaki R.
      • Ujiie M.
      • Hori N.
      • et al.
      Comparative study of adverse events after yellow fever vaccination between elderly and non-elderly travellers: questionnaire survey in Japan over a 1-year period.
      ,
      • Trubiano J.A.
      • Johnson D.
      • Sohail A.
      • Torresi J.
      Travel vaccination recommendations and endemic infection risks in solid organ transplantation recipients.
      in addition to those listed in Table 2.
      c Data from Plotkin's Vaccines
      • Finn T.M.
      • Egan W.
      Vaccine additives and manufacturing residuals in vaccines licensed in the United States.
      and manufacturer's vaccine package inserts for cholera (Vaxchora; PaxVac, Inc), meningococcal conjugate (Menactra; Sanofi Pasteur Inc), pneumococcal conjugate (Prevnar; Pfizer Inc), pneumococcal polysaccharide (Pneumovax; Merck & Co, Inc), and tick-borne encephalitis (FSME-Immun; Pfizer Inc).

      Risk Assessment for Vaccine Selection

      The choice of vaccines for an individual traveler is based on risk of exposure to VPDs on the chosen itinerary; the severity of disease, if acquired; and any risks presented by the vaccine itself. Risk of infection often varies within a risk country so that an exact itinerary needs to be ascertained during the pretravel consultation. Detailed references may need to be consulted (Table 3) for many itineraries. Specific risk and risk-taking behaviors related to travel style, type of accommodation, food, use of repellents, sexual behavior, and outdoor activities also affect risk of infection. Travel medicine physicians as well as travelers differ in their perception and tolerance of risk. Requests for immunization against diseases that are actually of negligible risk to the traveler but have the potential for poor outcome if acquired are often difficult for the physician to refuse because sporadic travel-related cases do occur each year.

      Administration of Travel Vaccines

      General best practices for adult vaccines are found elsewhere in this Mayo Clinic Proceedings vaccine thematic series.

      Hunter P, Adamson Fryhofer S, Szilagyi PG. Vaccination of adults in general medical practice. Mayo Clin Proc. In press.

      Several best practices are specific to travel vaccines. Testing may be useful to assess immunity to HA or HB virus in persons from countries with high endemicity or in persons with a history of jaundice or to assess immunity to measles, mumps, and rubella (MMR) in someone lacking documentation.
      • Turner D.P.
      • McGuinness S.L.
      • Cohen J.
      • Waring L.J.
      • Leder K.
      Use of pre-travel vaccine-preventable disease serology as a screening tool to identify patients in need of pre-travel vaccination: a retrospective audit.
      This scenario must be weighed against cost factors and possible loss to follow-up in those busy preparing for travel. Different brands of HA, HB (except Heplisav-B; Dynavax Technologies Corporation), rabies, and meningococcal ACYW-135 vaccine are interchangeable for subsequent doses if necessary. Acyclovir and related drugs and influenza antivirals (neuraminidase and polymerase inhibitors) preclude concomitant use of live attenuated varicella and zoster vaccines and influenza vaccines, respectively, but not YF vaccine. Antibacterial drugs should not be given within 3 days of a dose of live oral typhoid or 14 days prior to oral cholera vaccine. Anaphylactic egg allergy precludes administration of YF and MMR vaccines, which contain more egg protein than influenza vaccines. No current vaccine contains penicillin. Women who are breastfeeding newborns and infants should avoid YF vaccination but not other travel vaccines. Translations of VPD terms in multiple languages are available when travelers provide foreign-language vaccine records.
      Immunization Action Coalition
      Quick chart of vaccine-preventable disease terms in multiple languages.
      An interruption in a vaccination schedule generally does not require restarting the entire vaccine series, nor does it require the addition of extra doses.
      • Kroger A.T.
      • Duchin J.
      • Vázquez M.
      General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP).
      The series should be continued with the next dose in the series, and any subsequent doses should be administered at the same interval as if the series had not been interrupted. Rabies and oral typhoid vaccines present exceptions to this rule but still have some overall flexibility. All currently used immunizations may be given at the same time and in any combination. If 2 live viral antigens are not administered on the same day, they must be spaced by a month. Live oral vaccines (typhoid, cholera, polio) can be administered at any interval with respect to any live virus vaccine. Baseline purified protein derivative skin tests or interferon-γ release assays, often done in the pretravel setting, can be given on the day that live virus vaccines are administered or else must be done more than 4 weeks later.

      Routine Vaccines Often Administered in the Travel Clinic

      This section considers routine vaccines that are normally readministered at regular intervals or vaccine series that need to be finished in a healthy adult regardless of the current plans for international travel and when there are no specific medical or behavioral risk factors. The text of this and the next 2 sections provides general information on vaccine indications and logistic issues that arise in the clinic and complement the information in Table 2. Full details of routine adult immunization are found elsewhere in this Mayo Clinic Proceedings vaccine thematic series.

      Hunter P, Adamson Fryhofer S, Szilagyi PG. Vaccination of adults in general medical practice. Mayo Clin Proc. In press.

      Verification and update of these routine vaccines, regardless of itinerary, is part of the pretravel consultation. However, for many VPDs, the risk of disease is also increased in developing countries.

      Tetanus-Diphtheria–Acellular Pertussis

      If no adult doses of tetanus-diphtheria–acellular pertussis have ever been given, a dose is indicated regardless of the time elapsed since the last tetanus-diphtheria vaccination, but travelers to remote areas where tetanus toxoid (indicated in cases of dirty trauma) will be inaccessible should get boosters at 5-year intervals. Trauma during travel is common, and unsafe needles or uncertain vaccine quality at the destination is another reason for assuring immunity pretravel. Although immunity to tetanus after a primary childhood vaccination series tends to be very long-lived, the short-lived immunity to diphtheria and pertussis conferred by vaccination mandates strict validation of vaccine history and booster doses according to schedule. Evidence indicates that pertussis immunity, at least in children and adolescents, is significantly shorter than the standard 10-year interval, but no special accelerated dosing guidelines for travelers at very high risk of pertussis exposure exist.
      • Liang J.L.
      • Tiwari T.
      • Moro P.
      • et al.
      Prevention of pertussis, tetanus, and diphtheria with vaccines in the United States: recommendations of the Advisory Committee on Immunization Practices (ACIP).

      Varicella

      Varicella, which is highly contagious, is primarily a disease of adolescents and young adults in tropical, nonindustrialized countries.
      • Rice P.S.
      Ultra-violet radiation is responsible for the differences in global epidemiology of chickenpox and the evolution of varicella-zoster virus as man migrated out of Africa.
      Two doses of varicella vaccine, administered at least 4 weeks apart, should be considered for adult travelers without evidence of varicella immunity. Adults born before 1980 in the United States are considered immune.

      Zoster

      Data are lacking to determine whether travel poses additional risk for shingles due to reactivation of varicella zoster virus. The newly approved recombinant zoster vaccine should be given to all adults aged 50 years and older regardless of travel plans and regardless of having received a previous dose of the live zoster vaccine.
      • Dooling K.L.
      • Guo A.
      • Patel M.
      • et al.
      Recommendations of the Advisory Committee on Immunization Practices for use of herpes zoster vaccines.

      Pneumococcal

      Travelers are at increased risk of all types of respiratory infections. Healthy travelers who are 65 years of age or older should be current with pneumococcal vaccination with sequential doses of PCV13 and PPSV23. Beginning in 2019, ACIP no longer recommends routine (now optional) PCV13 for healthy nontraveler adults 65 years and older. Travelers may face PCV13 strains at their destinations making travel an indication for PCV13 in this age cohort. A minimum interval of 8 weeks (as used for patients with underlying medical conditions) between a dose of Pneumovax 23 (Merck & Co, Inc) (if indicated) and a previously given dose of Prevnar 13 (Pfizer Inc) may be used to ensure optimal immunity of healthy travelers 65 years of age and older needing maximal protection prior to the trip.
      • Centers for Disease Control and Prevention (CDC)
      Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine for adults with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      No data support an advantage of the current 1-year over an 8-week PCV13 to PPSV23 interval in healthy individuals; the 1-year interval was introduced solely for a number of logistic considerations.
      • Kroger A.T.
      • Duchin J.
      • Vázquez M.
      General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP).

      Human Papillomavirus

      Substantial evidence of increased rates of sexual activity, often unplanned, during travel exists. No specific indication for travelers has been studied or recommended, but all travelers in the indicated age groups (now includes optional vaccinaition for males and females age 27-45) for human papillomavirus vaccination should be fully immunized according to standard schedules.

      Routine Adult Vaccines With Additional Travel Indications

      Measles-Mumps-Rubella

      Imported measles and mumps have caused travel-related outbreaks in the United States, and nonimmune adult US travelers are at significant risk, including in Western Europe and Mexico.
      • Leong W.Y.
      Measles cases hit record high in Europe in 2018.
      • Bednarczyk R.A.
      • Rebolledo P.A.
      • Omer S.B.
      Assessment of the role of international travel and unauthorized immigration on measles importation to the United States.
      Persons (except traveling health care workers) born in the United States before 1957 or born at any time in the developing world are considered immune to measles; other adult travelers should have received a lifetime total of at least 2 doses of live measles–containing vaccine during their life, unless measles immunity can be documented (definitive laboratory evidence of acute infection or current antibody titers). Two doses of MMR should be considered for health care or humanitarian workers without other evidence of immunity. A third lifetime dose of MMR vaccine may be given during specific mumps outbreak situations.
      • Cardemil C.V.
      • Dahl R.M.
      • James L.
      • et al.
      Effectiveness of a third dose of MMR vaccine for mumps outbreak control.
      Many persons born in the United States before 1970 have not been vaccinated with MMR at all, and many born in the 1970s have not received the second dose in the series, which has been in the guidelines only since 1990. Children who are 6 to 11 months of age need one dose of MMR prior to travel regardless of destination country. This dose is noncountable, and 2 doses still should be given at the recommended ages (at least 28 days apart).

      Hepatitis B

      Travelers born in the United States after 1992 will most often already have received an HB vaccine series. For previously nonimmune travelers, pretravel HB vaccination is indicated for all nonvaccinated travelers with standard indications, such as health care workers, and also for all longer-stay travelers who will be visiting or residing in high- or moderate-risk areas. Transmission via routes such as sexual contact, blood transfusions, contaminated medical equipment, body piercing, tattooing, and acupuncture is difficult to control or predict in the context of travel. Vaccination is usually advocated for short-term travelers, especially younger travelers and those anticipating close contact with local populations, even if they have no specific risk factors. Adventure travelers who are by definition at high risk of injury, as well as backpackers and those with underlying medical conditions, are more likely to require contact with the medical system. Business and other frequent travelers who take multiple short trips have a cumulative risk that increases with time,
      • Leder K.
      • Chen L.H.
      • Wilson M.E.
      Aggregate travel vs. single trip assessment: arguments for cumulative risk analysis.
      and such individuals should receive the HB vaccine. Persons likely to engage in future international travel should consider a vaccine that confers lifelong protection.
      Accelerated and hyperaccelerated schedules (Table 2) are used widely in travel medicine practice and are approved in many countries. These schedules are not as well known among pharmacists and primary care clinicians, so travelers in whom an accelerated series is initiated may have difficulty completing them when seeking subsequent doses at a location other than a dedicated travel clinic. For conventional HB vaccines, all 3 primary doses before travel are necessary for high assurance of protection. A newly licensed HB vaccine, Heplisav-B, which is not yet widely integrated into clinical practice, produces protection with a standard schedule of 2 doses spaced by 1 month, making it especially convenient for travelers.
      • Jackson S.
      • Lentino J.
      • Kopp J.
      • et al.
      HBV-23 Study Group
      Immunogenicity of a two-dose investigational hepatitis B vaccine, HBsAg-1018, using a toll-like receptor 9 agonist adjuvant compared with a licensed hepatitis B vaccine in adults.
      • Schillie S.
      • Vellozzi C.
      • Reingold A.
      • et al.
      Prevention of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practices.
      With the overlap of indications for use of the individual vaccines, the combined HA and HB vaccine provides convenience for travelers and has a licensed accelerated 3-week schedule (Table 2).
      • Van Damme P.
      • Leroux-Roels G.
      • Suryakiran P.
      • Folschweiller N.
      • Van Der Meeren O.
      Persistence of antibodies 20 y after vaccination with a combined hepatitis A and B vaccine.

      Influenza

      Influenza is the most common VPD of travelers, especially those on cruise ships and those going to mass-gathering events such as the Hajj pilgrimage.
      • Goeijenbier M.
      • van Genderen P.
      • Ward B.J.
      • Wilder-Smith A.
      • Steffen R.
      • Osterhaus A.D.
      Travellers and influenza: risks and prevention.
      Vaccination clearly protects against influenza complications such as pneumonia, hospitalization, or death even if some breakthrough respiratory illness does occur. Influenza virus circulates year-round in tropical and subtropical regions, and influenza season occurs in winter in temperate regions in the Southern Hemisphere (which is summer in the Northern Hemisphere). All travelers visiting the tropics at any time of year and visiting temperate countries where it is currently winter should be current on the most recent influenza vaccine available at home before the trip. Vaccine will not protect for at least 1 week postimmunization. Recent evidence suggests that travelers immunized with the current vaccine formulation more than 6 months earlier may consider revaccination because immunity clearly declines to close to zero by this time.
      • Young B.
      • Sadarangani S.
      • Haur S.Y.
      • et al.
      Semiannual versus annual influenza vaccination in older adults in the tropics: an observer-blind, active-comparator–controlled, randomized superiority trial.
      Data supporting revaccination is limited but enticing.
      Travelers may consider baloxavir or oseltamivir as standby therapy, especially for those who are at high risk for complications from influenza or who are inadequately vaccinated. Travelers who carry baloxavir or oseltamivir should be advised to make every effort to institute therapy only under medical advice. This advice could be obtained at the destination or after telephone consultation with the prescribing physician at home. In China and Southeast Asia, avoiding poultry markets and farms may decrease risk of avian influenzas such as H7N9, H5N1, and H5N6, against which currently available vaccines are ineffective; in vitro data indicate efficacy of baloxavir against all the aforementioned avian influenza strains.

      Meningococcal

      Quadrivalent (ACWY) meningococcal vaccine is recommended for travelers to Africa's sub-Saharan “meningitis belt” (Figure 2) during the dry season from December through June, especially if prolonged contact with the local population is likely. Health care workers to the meningitis belt might consider vaccination year-round. Out-of-season epidemics have occurred in Ethiopia, Somalia, and Tanzania. Muslims undertaking Hajj and Umrah pilgrimages in Saudi Arabia are at a higher risk of meningococcal disease, and proof of current vaccination with quadrivalent vaccine within the previous 5 years is required to obtain pilgrimage visas. Immunity to some serotypes in the tropics may wane in as little as 3 years, a consideration for most travelers to the developing world not included in US recommendations.
      • Baxter R.
      • Baine Y.
      • Kolhe D.
      • Baccarini C.I.
      • Miller J.M.
      • Van der Wielen M.
      Five-year antibody persistence and booster response to a single dose of meningococcal A, C, W and Y tetanus toxoid conjugate vaccine in adolescents and young adults: an open, randomized trial.
      • Cohn A.C.
      • MacNeil J.R.
      • Harrison L.H.
      • et al.
      Active Bacterial Core Surveillance (ABCs) Team and MeningNet Surveillance Partners
      Effectiveness and duration of protection of one dose of a meningococcal conjugate vaccine.
      Many travel advisors recommend revaccination after 3 years for very high-risk travelers. Meningococcal B vaccine is not indicated for travel unless the traveler has another routine indication such as asplenia or complement deficiency. The incidence of meningococcal B infection is not increased in developing countries when compared with the United States.
      • Sridhar S.
      • Greenwood B.
      • Head C.
      • et al.
      Global incidence of serogroup B invasive meningococcal disease: a systematic review.
      Sporadic outbreaks may occur, as in the United States, so if a traveler was going to a closed setting such as a school outbreak, vaccination could be considered.

      Polio

      Because of eradication efforts, poliomyelitis remains endemic in only Afghanistan, Pakistan, and Nigeria, but complete control remains elusive. A handful of other countries periodically have outbreaks of human polio cases due to circulating vaccine-derived polio viruses. Adults who have previously completed a primary vaccine series and plan to travel to countries that are polio-endemic or have had cases of vaccine-derived polio in the previous year (updated information is available from the Global Polio Eradication Initiative
      Global Polio Eradication Initiative
      ) should receive a one-time single dose of inactivated polio vaccine as a booster. Completely unvaccinated adults traveling to risk countries may need to receive an entire primary series prior to the trip. However, even a single dose is beneficial. Revaccination with an inactivated polio vaccine primary series may be needed for a child who had been vaccinated with a routine oral polio vaccine series outside the United States. Vaccination is occasionally required for travelers going to certain polio-free countries that have a mandatory entry requirement for travelers (residents or long-stay visitors) coming from countries on a defined list of suspected polio-endemic countries.
      Centers for Disease Control and Prevention
      Travelers' Health. Vaccines. Medicines. Advice.

      Travel-Only Vaccines for Adults

      Hepatitis A and typhoid vaccines are considerations for most travelers to developing countries. The remaining vaccines in this section are indicated for specific risk areas (Figure 2) and for specific risk activities within the specified countries, with the exception of YF.

      Hepatitis A

      Unless routine or catch-up vaccination has been administered since 2005, young adults in the United States generally have little to no immunity to HA. Hepatitis A vaccine is indicated for every nonimmune traveler to countries or areas with moderate to high risk of infection, which includes essentially every destination other than the United States, Canada, Japan, Australia, New Zealand, Scandinavian countries, and developed countries in Europe. A single dose of HA vaccine given any time before travel, even on the way to the airport, provides adequate protection to the healthy adult. The Centers for Disease Control and Prevention (CDC) recommends ancillary concomitant immunoglobulin for travelers older than 40 years who are planning to depart in 2 weeks or less, but this recommendation has not been widely adopted in practice. Individuals born in the developing world may already be immune to HA. Persons with a history of hepatitis or who previously lived in an endemic country for a prolonged period may benefit from prevaccination serum antibody testing.
      • Turner D.P.
      • McGuinness S.L.
      • Cohen J.
      • Waring L.J.
      • Leder K.
      Use of pre-travel vaccine-preventable disease serology as a screening tool to identify patients in need of pre-travel vaccination: a retrospective audit.
      Nevertheless, they merit HA vaccine unless immunity can be confirmed. When considering the combination HA/HB vaccine, the accelerated schedule should not be used unless at least 2 doses can be given prior to departure because the combination vaccine contains half of the HA antigen compared with that in a dose of monovalent adult HA vaccine. In this circumstance, monovalent HA and HB vaccines should be administered separately. Infants aged 6 to 11 months should be given one dose (noncountable) prior to travel.
      • Nelson N.P.
      • Link-Gelles R.
      • Hofmeister M.G.
      • et al.
      Update: recommendations of the Advisory Committee on Immunization Practices for use of hepatitis A vaccine for postexposure prophylaxis and for preexposure prophylaxis for international travel.
      Following this dose, routine vaccination with HA vaccine (2 additional age-appropriate doses) should be administered. When pretravel vaccination cannot be given, intramuscular immunoglobulin dosing is (1) 0.1 mL/kg for trips of less than 1 month's duration, (2) 0.2 mL/kg for trips of less than 2 months, and (3) 0.2 mL/kg every 2 months for trips of 2 months or longer.
      For unvaccinated travelers who have had a specific HA exposure while traveling, a single dose of HA vaccine for postexposure prophylaxis is now recommended for all persons aged 12 months or older, preferably within 2 weeks of exposure; additionally, immunoglobulin (if available) may be administered to immunocompromised adults of all ages as well as to those older than 40 years, depending on the physician's risk assessment (eg, chronic liver disease, risk level of the exposure).
      • Nelson N.P.
      • Link-Gelles R.
      • Hofmeister M.G.
      • et al.
      Update: recommendations of the Advisory Committee on Immunization Practices for use of hepatitis A vaccine for postexposure prophylaxis and for preexposure prophylaxis for international travel.
      • Link-Gelles R.
      • Hofmeister M.G.
      • Nelson N.P.
      Use of hepatitis A vaccine for post-exposure prophylaxis in individuals over 40 years of age: a systematic review of published studies and recommendations for vaccine use.

      Typhoid

      Typhoid vaccine is indicated for all travelers to the Indian subcontinent and considered for those traveling to other endemic areas (Figure 2) under all but the most deluxe and protected conditions. Risk increases with trip duration, lodging and/or eating with local residents, and extent of travel off the usual tourist itineraries. In risk areas, food and water precautions should still be followed rigorously because typhoid vaccines are only 53% to 72% protective, and a large oral inoculum may overwhelm even an optimal antibody response.
      • World Health Organization
      Typhoid vaccines: WHO position paper, March 2018 - recommendations.
      The recent increase in quinolone-resistant Salmonella enterica serotype Typhi in Asia and extremely resistant typhoid in Pakistan has decreased the threshold for typhoid vaccination because infection, once acquired, may require inpatient parenteral therapy with sophisticated antibiotics. Current typhoid vaccines do not protect against S enterica serotype Paratyphi, which is emerging in many areas. Adherence to the oral vaccine regimen may be as low as 70%. Although revaccination with the injectable Vi polysaccharide vaccine is recommended by the US Food and Drug Administration every 2 years, revaccination every 3 years is recommended in Canada, Australia, the United Kingdom, and other countries if continued or repeated exposure exists.

      Yellow Fever

      The main indication for YF vaccination is to prevent infection in individuals at risk. However, YF is currently the only vaccine that falls under the International Health Regulations (IHR) that may necessitate vaccination purely for regulatory reasons. Neither YF vaccine nor any other vaccine is currently required on return to the United States. In general, all healthy adult travelers to areas with a risk of YF transmission (Figure 2) should be vaccinated. This endemic area may be restricted to only a portion of a country. Because of rare but serious vaccine-associated adverse effects, persons who are not at any risk of exposure should not be vaccinated. Only first doses of YF vaccine, but not booster doses, are associated with rare but severe or fatal adverse events. The overall rate is 1 event per 334,000 doses,
      • Lindsey N.P.
      • Rabe I.B.
      • Miller E.R.
      • Fischer M.
      • Staples J.E.
      Adverse event reports following yellow fever vaccination, 2007-13.
      but severe events occur most frequently in persons older than 60 years (increasing with advancing age) and in any person with a thymus disorder.
      • Staples J.E.
      • Bocchini Jr., J.A.
      • Rubin L.
      • Fischer M.
      Yellow fever vaccine booster doses: recommendations of the Advisory Committee on Immunization Practices, 2015.
      • Lindsey N.P.
      • Rabe I.B.
      • Miller E.R.
      • Fischer M.
      • Staples J.E.
      Adverse event reports following yellow fever vaccination, 2007-13.
      Urban YF rarely occurs in South America, but the situation is currently evolving in Brazil and up-to-date maps should be checked. Persons who have anything less than a definite, fixed itinerary and who will travel anywhere close to regions with risk of transmission should be vaccinated. Decisions about YF vaccination depend on risk-benefit for the person, the itinerary, and the destination country entry requirements.
      A number of African countries and one in South America (French Guiana) require proof of YF vaccination from all arriving travelers. Other countries, both within and outside the risk zone, have submitted more complex requirements to the World Health Organization (WHO). They may require an official vaccination certificate only for individuals arriving directly from or via a country in the YF endemic zone but not from travelers arriving from other countries. Such transits may include even an airplane connection in an affected country. These YF-free countries usually have the conditions and vectors to initiate a YF transmission cycle, and the purpose of the vaccine requirement is to prevent entry of viremic travelers. Current country-by-country YF entry requirements are available from the WHO.
      • World Health Organization
      International travel and health: information about yellow fever vaccination requirement.
      The requirement often applies even if the arriving traveler has not visited an area within a country of departure that is endemic for YF.
      A special permit, obtainable in the United States from state health departments, is required to legally stamp an international certificate of vaccination as being from an authorized YF vaccine center. The IHR specify that clinicians who decide that YF vaccine is contraindicated on medical grounds can provide a letter stating the reasons for an exemption, which is shown on arrival at the destination. Acceptance of a “waiver letter” depends on the discretion of the authorities at the port of entry. On arrival, the destination country may also quarantine the traveler for up to 6 days or request that the traveler be placed under surveillance. The variable risk within the endemic regions of the world must be considered (in consultation with an expert, if necessary), and cancellation of travel should be recommended strongly if the risk is more than negligible and YF vaccine cannot be given or is declined by the traveler. A YF certificate becomes valid for entry 10 days after it is stamped and dated.
      The YF vaccine has until several years ago been thought to provide protection for 10 years. Currently, the CDC recommends that 10-year boosters should be restricted to healthy travelers planning a long stay in any country with any risk of YF transmission, to all travelers spending any amount of time in high-risk areas (notably West Africa), and to all persons going to locations with a current outbreak. A CDC analysis found that 92% of vaccine recipients have virus-neutralizing antibody at 10 years and 80% have the antibody at 20 years. Thus, almost all healthy persons appear to have long-term immunity.
      • Staples J.E.
      • Bocchini Jr., J.A.
      • Rubin L.
      • Fischer M.
      Yellow fever vaccine booster doses: recommendations of the Advisory Committee on Immunization Practices, 2015.
      For the purposes of the IHR, documentation of a single dose of YF vaccine at any time during the person's life suffices for entry to any country.

      Rabies

      A preexposure rabies series is indicated for long-stay travel to endemic areas of Latin America, Asia, or Africa, where the rabies threat is constant and access to adequate postexposure rabies immunoglobulin and vaccine is likely to be limited. Preexposure vaccination does not eliminate the need for vaccination after an exposure. However, it dramatically simplifies the postexposure vaccine schedule to 2 injections and eliminates the need for rabies immunoglobulin, which is often very difficult to access abroad. Countries with the highest risk of rabies include the Indian subcontinent, Thailand, Vietnam, and most sub-Saharan African countries. For short-term travel, risk groups for whom immunization should be considered include adventure travelers, bikers, hikers, cave explorers, or business travelers who travel for short but frequent trips and plan to go running outdoors on these trips. Regardless of vaccination status, travelers should be instructed to cleanse well with soapy water any bite or animal scratch involving broken skin immediately and to seek postexposure treatment for rabies within a maximum of 48 hours. Seeking quality biologicals and additional postexposure vaccine doses is critical to prevent rabies. In 2018, the WHO recommended that preexposure prophylaxis rabies regimens can be shortened to intradermal rabies vaccine at 2 separate sites on 2 visits (days 0 and 7).
      Rabies vaccines: WHO position paper – April 2018.
      Recent evaluations add support to the reduced-dose preexposure prophylaxis.
      • Jonker E.F.F.
      • Visser L.G.
      Single visit rabies pre-exposure priming induces a robust anamnestic antibody response after simulated post-exposure vaccination: results of a dose-finding study.
      • Langedijk A.C.
      • De Pijper C.A.
      • Spijker R.
      • Holman R.
      • Grobusch M.P.
      • Stijnis C.
      Rabies antibody response after booster immunization: a systematic review and meta-analysis.
      • Chen L.H.
      • Gautret P.
      • Visser L.G.
      Rabies preexposure prophylaxis: application of updated World Health Organization position to travelers.
      • Soentjens P.
      • Andries P.
      • Aerssens A.
      • et al.
      Preexposure intradermal rabies vaccination: a noninferiority trial in healthy adults on shortening the vaccination schedule from 28 to 7 days.
      Changes to existing national guidelines (0, 7, 28 days, intramuscular dosing) in major countries (United States, Canada, Australia, France) have yet to be considered; the United Kingdom has formally considered the WHO advice and has elected to stay with the status quo.

      Japanese Encephalitis

      Japanese encephalitis is endemic to many rural farming areas of Southeast Asia and the Indian subcontinent (Figure 2). Sporadic cases with severe sequelae continue to occur in travelers. Overall risk is very low for short-stay travelers and for those who confine their travel to urbanized areas or brief daytime rural exposures during typical tourist excursions. However, cases may be sporadic and have occurred in short-stay visitors traveling out of season whose only rural travel had been to beach resorts. In temperate regions, the transmission season is from April through November. In tropical or subtropical regions of Oceania and Southeast Asia, transmission may occur year-round. Vaccination is recommended for (1) long-stay travel to an endemic rural area, (2) expatriation to anywhere in an endemic country, (3) short-term travel to endemic rural areas with potential unprotected outdoor exposure, such as with adventure travel, or (4) short-term travel during a current local epidemic.
      • Cramer J.P.
      • Jelinek T.
      • Paulke-Korinek M.
      • et al.
      One-year immunogenicity kinetics and safety of a purified chick embryo cell rabies vaccine and an inactivated Vero cell-derived Japanese encephalitis vaccine administered concomitantly according to a new, 1-week, accelerated primary series.

      Cholera

      Cholera vaccination is no longer required by any country, and the risk to typical travelers is insignificant. However, aid, refugee, and health care workers in areas where cholera is endemic or epidemic may consider cholera vaccine. A live attenuated oral cholera vaccine was approved in 2016 by US Food and Drug Administration for use only in immunocompetent adults in the United States; duration of immunity is unknown at present.
      • Wong K.K.
      • Burdette E.
      • Mahon B.E.
      • Mintz E.D.
      • Ryan E.T.
      • Reingold A.L.
      Recommendations of the Advisory Committee on Immunization Practices for use of cholera vaccine.
      A highly effective oral, killed, whole-cell–B subunit cholera vaccine is available widely outside the United States. This vaccine also has about 50% efficacy against enterotoxigenic Escherichia coli and a 7% to 23% efficacy against all traveler's diarrhea, but this indication is not generally recommended by authoritative sources.

      Tick-Borne Encephalitis

      Tick-borne encephalitis is an emerging, important, and serious flavivirus central nervous system infection in endemic areas. Distribution is highly focal in a range that extends in a swath from Germany through Scandinavia and the Baltic states to Siberia and Vladivostok in the east. Risk to travelers is low unless extensive outdoor activities are planned in forested regions in endemic areas. Immunization against tick-borne encephalitis is recommended for adventure travel, extensive outdoor exposure, or camping in the forests of the endemic countries between April and October. Tick precautions are also recommended. The vaccine is available in most endemic countries but not in the United States or Canada.
      World Health Organization. Vaccines against tick-borne encephalitis: WHO position paper.
      • Aerssens A.
      • Cochez C.
      • Niedrig M.
      • Heyman P.
      • Kühlmann-Rabens I.
      • Soentjens P.
      Analysis of delayed TBE-vaccine booster after primary vaccination.
      Three to 4 weeks are required for accelerated vaccination and development of immunity, making vaccination on arrival impractical for short-stay travelers.

      Travel Vaccines for Special Populations

      Immunocompromised travelers and travelers living with HIV comprise up to 4% of travelers seen in some US travel clinics and pursue itineraries largely similar to those of immunocompetent travelers.
      • Hochberg N.S.
      • Barnett E.D.
      • Chen L.H.
      • et al.
      International travel by persons with medical comorbidities: understanding risks and providing advice.
      Different conditions and medications produce widely varying degrees of immunocompromise, and there are many unknowns in this field. Guidance regarding vaccination of immunocompromised travelers is less evidence-based than with other categories of travelers. Health hazards at the destination that would exacerbate the underlying condition can be more severe in an immunocompromised traveler.
      Advice from a specialized travel clinic is of benefit for persons who are severely immunocompromised (transplants, active malignancy, congenital immunodeficiency) or have underlying chronic disease, especially those who are planning to live abroad for a long time or who have complicated itineraries.
      Travelers with autoimmune diseases (eg, systemic lupus erythematosus, inflammatory bowel disease, rheumatoid arthritis, multiple sclerosis) who are not being treated with immunosuppressive or immunomodulatory drugs are not considered significantly immunocompromised, but definitive data are lacking.
      Immunocompromised persons including those taking immunosuppressive drugs and most biological response–modifying drugs should not receive live vaccines.
      • Hall V.
      • Johnson D.
      • Torresi J.
      Travel and biologic therapy: travel-related infection risk, vaccine response and recommendations.
      • Kotton C.N.
      • Kroger A.T.
      • Freedman D.O.
      Immunocompromised travelers.
      • Kroger A.T.
      • Duchin J.
      • Vázquez M.
      General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP).
      • Rubin L.G.
      • Levin M.J.
      • Ljungman P.
      • et al.
      2013 IDSA clinical practice guideline for vaccination of the immunocompromised host.
      In the context of specific travel vaccines, this includes YF, MMR, oral cholera, and oral typhoid. Asplenia is not a contraindication for live viral vaccines. Nonlive vaccines, although safe, may have suboptimal efficacy in immunocompromised hosts, and the implications of this issue should be discussed with the traveler. In general, such vaccines are indicated because of specific risk of potentially serious infection at the destination.
      Unvaccinated travelers with severe immune compromise should be strongly discouraged from travel to destinations that present a true risk for YF. If travel is unavoidable to an area where YF vaccine is recommended for personal protection and the vaccine has not been given, these travelers should be informed of the risk of YF and carefully instructed in methods to avoid mosquito bites.
      Significant immunosuppression is a contraindication to YF vaccination.
      • Lindsey N.P.
      • Rabe I.B.
      • Miller E.R.
      • Fischer M.
      • Staples J.E.
      Adverse event reports following yellow fever vaccination, 2007-13.
      Recent data suggest that YF vaccination before solid organ transplant, even long before transplant, generally provides protective antibody levels after transplant. Patients with asymptomatic HIV or CD4 cell counts greater than 200/mL may be offered YF vaccine if travel to YF-endemic areas is unavoidable; recipients should be monitored closely for possible adverse effects. Patients with undetectable viral loads respond well to YF vaccination regardless of CD4 cell count. Because vaccine response may be suboptimal, such vaccinees are candidates for serologic testing 1 month after vaccination. If international travel requirements, and not true exposure risk, are the only reasons to vaccinate a traveler with asymptomatic HIV infection or a limited immune deficit, the physician should provide a waiver letter.
      The period of time clinicians should wait after discontinuation of immunosuppressive therapies before administering a live vaccine such as YF is not consistent across all live vaccines. No specific data exist for the safety or efficacy of YF vaccine in this regard. For cancer chemotherapy, radiation therapy, and highly immunosuppressive medications (exclusive of lymphocyte-depleting agents and organ transplant immunosuppression), the waiting period is 3 months.
      • Hall V.
      • Johnson D.
      • Torresi J.
      Travel and biologic therapy: travel-related infection risk, vaccine response and recommendations.
      • Kotton C.N.
      • Kroger A.T.
      • Freedman D.O.
      Immunocompromised travelers.
      • Kroger A.T.
      • Duchin J.
      • Vázquez M.
      General Best Practice Guidelines for Immunization: Best Practices Guidance of the Advisory Committee on Immunization Practices (ACIP).
      • Rubin L.G.
      • Levin M.J.
      • Ljungman P.
      • et al.
      2013 IDSA clinical practice guideline for vaccination of the immunocompromised host.
      For lymphocyte-depleting agents (alemtuzumab and rituximab), the waiting period is 6 months or more, although some experts believe the waiting period should be 1 year or more. For corticosteroid regimens considered immunosuppressive, the waiting period is 1 month. Restarting immunosuppression after live vaccination has not been studied, but some experts would recommend waiting at least 1 month.
      Immunocompromised travelers may require additional nontravel vaccines compared with healthy travelers. All travelers are at increased risk of respiratory illness. Unvaccinated persons who have the accepted routine indications for the pneumococcal vaccines, which includes most individuals with chronic disease and immunocompromising conditions, should receive this vaccine during the pretravel consultation if not already done.
      • Centers for Disease Control and Prevention (CDC)
      Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine for adults with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      • Centers for Disease Control and Prevention (CDC)
      Use of 13-valent pneumococcal conjugate vaccine and 23-valent pneumococcal polysaccharide vaccine among children aged 6-18 years with immunocompromising conditions: recommendations of the Advisory Committee on Immunization Practices (ACIP).
      Adult asplenic or functionally asplenic individuals often arrive at the clinic incompletely vaccinated against meningococcal disease (ACWY and B), Haemophilus influenzae type B, and pneumococcal infection. Asymptomatic adults with HIV and reconstituted CD4 cell counts of more than 200/mL are considered to have limited immune deficits and should receive additional vaccines according to the usual guidelines found elsewhere in this Mayo Clinic Proceedings vaccine thematic series.

      Hunter P, Adamson Fryhofer S, Szilagyi PG. Vaccination of adults in general medical practice. Mayo Clin Proc. In press.

      The HB vaccine high-dose regimen is recommended for all immunocompromised persons and adult hemodialysis patients.
      • Schillie S.
      • Vellozzi C.
      • Reingold A.
      • et al.
      Prevention of hepatitis B virus infection in the United States: recommendations of the Advisory Committee on Immunization Practices.
      Titers should be determined for HB surface antibody response after vaccination; patients should be revaccinated if response is absent. Immunocompromised travelers may have inadequate seroconversion after a single dose of HA vaccine.
      • Garcia Garrido H.M.
      • Wieten R.W.
      • Grobusch M.P.
      • Goorhuis A.
      Response to hepatitis A vaccination in immunocompromised travelers.
      Efforts should be made to administer 2 doses over a 6-month period prior to their trip. Instead of concomitant immunoglobulin with the first dose, the approach of giving a second dose of vaccine at least 4 weeks after the first dose for time-constrained travelers who can get both doses before travel has been effective in selected studies.
      • Rosdahl A.
      • Herzog C.
      • Frösner G.
      • Norén T.
      • Rombo L.
      • Askling H.H.
      An extra priming dose of hepatitis A vaccine to adult patients with rheumatoid arthritis and drug induced immunosuppression - a prospective, open-label, multi-center study.

      Conclusion

      Vaccine-preventable diseases occur during travel, including in developed countries, and impact the need for otherwise routinely recommended immunizations as well as for specific travel immunizations based on destinations or activities. The pretravel evaluation is an ideal setting to update all age-appropriate immunizations and provide protection against travel-associated diseases. Malaria chemoprophylaxis and education is an additional critical component of the pretravel health encounter. Prevention of other potential risks such as traveler's diarrhea, altitude illness, and blood-borne and sexually transmitted pathogens should be addressed, and travelers should be prepared to recognize or self-manage certain illnesses should they arise.

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