Immunizations for travel

INTRODUCTION — 

Travelers are frequently at risk of exposure to infectious pathogens and should seek advice about immunizations and other necessary prophylaxis prior to departure [1,2]. Individuals should arrange a pretravel consultation with a specialized travel clinic or a primary care practice with expertise in travel medicine [3]. The traveler should bring a record of prior immunizations and an itinerary.

Issues related to immunizations for travelers are reviewed here. Other travel-related issues are discussed separately. (See "Travel advice" and "Prevention of malaria infection in travelers" and "Travelers' diarrhea: Treatment and prevention", section on 'Guidance for prevention'.)

RESOURCES FOR ADDITIONAL GUIDANCE

●United States Centers for Disease Control and Prevention (CDC) – Information on the indications, dosing, side effects, timing, and contraindications for immunizations in travelers are provided by the CDC in a biennial, Health Information for International Travel [2], with ongoing updates in an online version.

●World Health Organization (WHO) – The WHO also has online information that includes vaccines or dosing regimens approved outside the United States [4]. Information may be found on the CDC website and the WHO website. Guidance may also be found via GlobalTravEpiNet (GTEN), which has web-based tools for providers and patients based on CDC recommendations.

GENERAL PRINCIPLES — 

Immunizations for travelers may be divided into the following categories [1]:

●Travel immunizations – Travel immunizations include (table 1) (see 'Immunizations for travel' below):

•Immunization required under international health regulations (eg, yellow fever)

•Immunization to reduce risk of infection guided by travel plans (destination[s] and activities)

Guidance for destination-specific immunizations can be found at the CDC website.

Vaccine availability and guidelines for vaccine use differ between countries. A broad international perspective has been published by the World Health Organization (WHO) [4].

●Routine immunizations – Pretravel visits offer an opportunity to update routine vaccinations for travelers. (See 'Routine immunizations' below.).

These are discussed further separately. (See "Standard immunizations for nonpregnant adults" and "Immunizations during pregnancy" and "Standard immunizations for children and adolescents: Overview".)

Timing of the pretravel visit — Ideally, pretravel consultation should occur at least one month before travel, to allow time for thorough evaluation and for immunizations (some of which require more than one dose). For immunocompromised travelers, pretravel consultation as early as six months before travel may be beneficial because immune response may take longer to develop.

If this is not feasible, beneficial preventive measures and advice can be delivered even immediately before departure.  

When a traveler presents with insufficient time to complete a vaccination series, starting the series should be considered, with the understanding that only short-term or incomplete immunity may be achieved before travel.

Review medical history and travel plans — Immunization needs are based on the traveler's medical history, travel plans, and prior immunizations. Guidance for destination-specific immunizations can be found at CDC website. (See "Travel advice", section on 'Review medical history and travel plans'.)

Vaccine coadministration — Any combination of vaccines can be administered at a single appointment.

In general, coadministration of the most widely used vaccines (live and inactivated) produces similar rates of seroconversion and adverse reactions relative to separate vaccine administration; exceptions are outlined below [5]:

●Live vaccines

•Timing of live virus parenteral vaccines – These vaccines include chikungunya vaccine, measles, mumps, and rubella (MMR), varicella vaccine, yellow fever vaccine, and zoster vaccine live (ZVL). All live vaccines given by the same route may be coadministered on the same day or at least four weeks apart. This is important to avoid interference with the immune response to the vaccine administered second.

If travel plans preclude waiting four weeks between two different live vaccines administered by the same route, the second vaccine may be given, but the immune response may be blunted and the vaccine doesn't "count." As an example, if a patient receives intramuscular MMR then seeks yellow fever vaccine prior to departure, the yellow fever vaccine should be administered (and may confer some protection), but subsequently should be repeated.

•Timing of live oral or intranasal vaccines – Live virus oral or intranasal vaccines include oral typhoid vaccine, oral cholera vaccine, oral polio vaccine, and nasal influenza vaccine.

For coadministration of oral typhoid vaccine (Ty21a) and oral cholera vaccine (CVD 103-HgR; Vaxchora), the first dose of oral typhoid vaccine should be administered >8 hours after administration of oral live attenuated cholera vaccine due to interference by the CVD 103-HgR buffer.

Interference is not a potential problem for other live vaccines administered by these routes; these may be administered at any time relative to parenteral live vaccines.

•Timing of live vaccines relative to inactivated vaccines – Any live vaccine administered by any route may be administered at any time relative to inactivated vaccines.

•Timing of live vaccines relative to immune globulin – Live vaccines should be administered at least two weeks before or at least six months after immune globulin, due to the presence of interfering antibodies in the plasma derived immune globulin preparations.

●Adjuvanted vaccines – Adjuvanted vaccines include Heplisav-B [recombinant hepatitis B vaccine], Shingrix [recombinant zoster vaccine], Fluad [influenza vaccine], COVID vaccines, and Arexvy [recombinant respiratory syncytial virus vaccine]. Administration of adjuvanted vaccines may be associated with greater side effects; therefore, if more than one adjuvanted vaccine is needed, we suggest administration of adjuvanted vaccines on different days or at least in different arms.

●COVID-19 vaccine – In general, simultaneous administration of any COVID-19 vaccine with other vaccines is acceptable. For individuals who warrant both Mpox and COVID-19 vaccination, no interval is mandated but it is reasonable to wait four weeks between these vaccines due to increased risk of myocarditis and pericarditis after each vaccine [6].  

Vaccine documentation — A standard immunization form should be part of the patient's medical record; the dedicated immunization history available in electronic medical records should be complete for all patients. Details to be recorded include vaccine type, dose, date of administration, manufacturer, lot number, and site of administration. It is also important to document if a patient declines to receive any recommended vaccine.

IMMUNIZATIONS FOR TRAVEL

Chikungunya vaccine

●General principles – Chikungunya virus is a virus transmitted by mosquitoes that causes acute febrile polyarthralgia and inflammatory arthritis, as well as acute cutaneous eruptions and other systemic manifestations. The disease occurs in the America, Asia, and Africa.

●Indications

•The United States Advisory Committee on Immunization Practices (ACIP) recommends live attenuated chikungunya vaccine (IXCHIQ) for individuals ≥18 years of age traveling to a country or territory where there is a chikungunya outbreak [7].

•The ACIP advises consideration of IXCHIQ for the following individuals traveling to a region with evidence of chikungunya virus transmission within the last five years, in the absence of an outbreak as defined by United States Centers for Disease Control and Prevention (CDC) [8,9]:

-Individuals >65 years (particularly those with underlying medical conditions) who are likely to have at least two weeks of mosquito exposure

-All individuals with anticipated mosquito exposure for a cumulative of six months or more in the next two years

●Contraindications and precautions

•Contraindications – Contraindications to IXCHIQ include immunosuppression (it is a live virus vaccine) and history of severe allergic reaction (eg, anaphylaxis) to any component of IXCHIQ.

•Precautions – Precautions include:

-Adverse reaction – Chikungunya-like illness after vaccination has emerged as the primary safety outcome. This reaction consists of fever and one or more of the following: arthralgia or arthritis, myalgia, headache, back pain, rash, lymphadenopathy, certain neurological, or cardiac or ocular symptoms that occurred within 30 days after vaccination.

-Use in pregnancy – No data on immune response to vaccination during pregnancy are available. In general, pregnant individuals should avoid travel to a transmission area and vaccination should be deferred until after delivery. If vaccination is pursued, it should be avoided during the first trimester (until 14 weeks gestation) and after the 36^th week of gestation.

Non-pregnant vaccine recipients should be counseled to wait four weeks following vaccination before becoming pregnant.

-Vertical transmission – Vertical transmission of natural wild-type chikungunya from pregnant individuals with viremia at delivery is common and can cause potentially fatal chikungunya virus disease in neonates. It is unknown whether the vaccine virus can be transmitted vertically and cause fetal or neonatal adverse reactions.

●Formulations, dosing, and administration

•IXCHIQ – IXCHIQ is approved by both the United States Food & Drug Administration (FDA) and the European Medicines Agency (EMA). Vaccine trial data are discussed separately. (See "Chikungunya fever: Treatment and prevention", section on 'Vaccination'.)

For adults >18 years of age, dosing consists of a single dose (0.5 mL IM). No data on booster doses are available; high neutralizing antibody titers without waning have been reported at two years post-vaccination in 96.8 percent of vaccinees [10].

•PXVX0317 – PXVX0317 was approved by the FDA in 2025. It is discussed further separately. (See "Chikungunya fever: Treatment and prevention", section on 'Vaccination'.)

Cholera vaccine

●General principles – Cholera is a severe diarrheal illness caused by infection with the gram-negative bacterium Vibrio cholerae; it is transmitted through fecal contamination of water or food and can rapidly lead to dehydration and death. It is extremely rare among travelers [11]. (See "Cholera: Epidemiology, clinical features, and diagnosis".)

●Indications – CVD 103-HgR (Vaxchora) is a live attenuated oral cholera vaccine approved by the FDA and recommended by the ACIP for prevention of cholera caused by serogroup O1 in individuals 2 through 64 years of age traveling to an area of active cholera transmission [12,13]. Vaccination is not recommended in areas where only rare imported or sporadic cases have been reported. (See "Cholera: Treatment and prevention", section on 'Vaccination'.).

Groups that most warrant vaccination include aid, refugee, and health care workers in endemic and epidemic areas in proximity to displaced populations, especially in crowded camps and urban areas with unsanitary conditions.

Most people do not travel to areas of active cholera transmission, and most travelers are at extremely low risk for cholera infection.

●Contraindications and precautions – The safety and effectiveness of live attenuated oral cholera vaccine has not been established in immunocompromised individuals. The vaccine strain may be shed in the stool of recipients for at least seven days, with potential for transmission to nonvaccinated household contacts.

●Dosing and administration – CVD 103-HgR is administered as a single oral dose at least 10 days before travel to a cholera-affected area. It should be administered in the provider's office. It should not be reconstituted with tap water since chlorine kills the vaccine. Eating and drinking should be avoided for one hour before and after vaccine administration.

CVD 103-HgR should not be administered within two weeks of systemic antibiotics, which may be active against the vaccine strain. The vaccine should be administered at least 10 days prior to use of antimalarial prophylaxis with chloroquine.

For coadministration of oral typhoid vaccine (Ty21a) and oral cholera vaccine (CVD 103-HgR; Vaxchora), the first dose of oral typhoid vaccine should be administered >8 hours after administration of oral live attenuated cholera vaccine due to interference by the CVD 103-HgR buffer.

The duration of protection is unknown but is at least three months.

Dengue vaccine — Dengue virus infection is a mosquito-borne febrile illness that occurs in many regions around the world. There are no dengue vaccines available in the United States for travelers.

●Available vaccines

•TAK-003 (Qdenga; Takeda) is a live attenuated vaccine based on a mix of a DENV-2 backbone with three recombinant DENV-2 strains expressing surface proteins for DENV-1, DENV-3, and DENV-4. Qdenga can be given to dengue-naive individuals; it is approved and commercially available for travelers >4 years of age in Europe, the United Kingdom, Brazil, Argentina, Indonesia, and Thailand.

•CYD-TDV (Dengvaxia) was discontinued in 2024 and was never commercially available for travelers.

●Indications – National guidelines in non-endemic countries where TAK-003 is commercially available are likely to remain permissive rather than prescriptive pending further data. For travelers 17 to 60 years of age, the strongest indication consists of long-stay or frequent travel to the highest risk destinations in a previously infected (any serotype) traveler; the highest benefit is during an ongoing DENV1 or DENV2 or epidemic at travel destination. For seronegative travelers, the benefits of vaccination are lower; any protection against DENV3 and DENV4 is uncertain.

●Dosing and Administration – Dengue tetravalent vaccine (live, attenuated) 0.5 mL dose at a two-dose (0 and 3 months). Protection starts 14 days after the first dose. No safety data >60 years of age but equivalent efficacy inferred from immunobridging of antibody titers. No data on boosters.

Live vaccine is contraindicated in pregnancy, HIV, and immunosuppression.

Dengue vaccination is discussed further separately. (See "Dengue virus infection: Prevention and treatment", section on 'Prevention'.)

Hepatitis A vaccine — Hepatitis A is a viral infection transmitted via the fecal-oral route that can lead to liver failure in rare cases. It is common in areas where sanitation and personal hygiene may be poor, and it is one of the most common vaccine-preventable diseases. (See "Hepatitis A virus infection in adults: Epidemiology, clinical manifestations, and diagnosis".)

●Indications – Vaccination is warranted for travelers to countries with intermediate to high endemicity of hepatitis A. A list of countries is available on the CDC website. Some experts advise hepatitis A vaccination regardless of destination, given the potential risk of hepatitis A even in countries with low endemicity and the complexity of interpreting risk maps [14,15].

The ACIP recommends routine vaccination of children aged 12 to 23 months and catch-up vaccination for children and adolescents aged 2 to 18 years who have not previously received hepatitis A vaccine, irrespective of travel [16].

●Contraindications and precautions – Hypersensitivity to hepatitis A vaccine or any component of the formulation is a contraindication to vaccination. The hepatitis A vaccines are acceptable for use in pregnancy and for immunocompromised individuals [17,18].

●Dosing and administration

•Formulations – Two monovalent hepatitis A vaccines (HAVRIX or VAQTA) and one bivalent vaccine (hepatitis A and B; Twinrix) are available in the United States.

There is a combined hepatitis A virus and typhoid vaccine (Viatim, Vivaxim; not available in the United States).

•Dosing for adults

-Monovalent vaccine – The monovalent vaccines are administered as a single dose any time prior to departure travel, with a second dose 6 to 12 months later for lifelong immunity [19]. If the immunization schedule is interrupted, the second dose can be given without restarting the series. A series started with one brand of vaccine may be completed with the same or other brand of hepatitis A vaccine.

-Bivalent vaccine – The bivalent vaccine requires two doses before travel, with completion of the third dose 6 months after the first.

•Patients at increased risk for infection – Ideally, adults who are ≥40 years, are immunocompromised, or have chronic medical conditions (including liver disease), should make efforts to receive two doses of vaccine over a six-month period prior to travel. In select studies, administering a second vaccine dose at least four weeks after the first dose (for travelers who can get both doses before travel) has also been effective [17,20].

For patients in the above categories who are departing in less than two weeks, immune globulin could be administered with the first dose of HAV vaccine. However, enthusiasm for this approach is limited because of the large volume of intramuscular injection this entails. The IG dose varies according to planned duration of travel (0.1 mL/kg for travel up to one month, 0.2 mL/kg for travel up to two months, and, for travel duration more than two months, repeat doses of 0.2 mL/kg every two months) [21].

•Dosing for children – Children traveling outside the United States should receive hepatitis A vaccination sooner than the standard immunization schedule. Children aged 6 to 11 months should receive one dose (not countable toward routine vaccination schedule) of hepatitis A vaccine before departure. After this dose, routine vaccination with hepatitis A vaccine (two additional age-appropriate doses) should occur. (See "Standard immunizations for children and adolescents: Overview".)

Hepatitis B vaccine

●General principles – Hepatitis B is a viral infection transmitted by bodily fluid exposure that can lead to hepatic failure and/or hepatocellular carcinoma. It is estimated that there are more than 350 million hepatitis B virus (HBV) carriers in the world, of whom roughly one million die annually from HBV-related liver disease. (See "Epidemiology, transmission, and prevention of hepatitis B virus infection" and "Hepatitis B virus immunization in adults".)

●Indications – Vaccination against hepatitis B virus is universally recommended in the United States for all individuals <60 years and can be considered in older individuals as well. The vaccine should be considered for all nonimmune travelers since it may be difficult to assess risk during the pretravel consultation.

Vaccination is warranted for travelers to countries with intermediate to high endemicity of HBV (ie, with hepatitis B surface antigen [HBsAg] prevalence ≥2 percent); a list of countries is available on the CDC website. In addition, vaccination should be considered for travelers with potential contact with blood or bodily secretions, potential sexual contact, or potential need for medical or dental procedures while traveling. Risk groups include health care workers, adventure travelers, Peace Corps volunteers, missionaries, military personnel, and medical tourists [15].

●Contraindications and precautions – Hypersensitivity to hepatitis B vaccine or any component of the formulation is a contraindication to vaccination.

Hepatitis B vaccine can be administered to immunocompromised patients, although vaccine immunogenicity is lower in these groups [18]. For individuals with comorbidities that may interfere with seroconversion, antibody titers can be checked to ensure adequate vaccine response has occurred.

●Formulations, dosing and administration – Hepatitis B vaccines available in the United States include:

•Conventional recombinant hepatitis B vaccines (Recombivax HB, Engerix-B)

•CpG-adjuvanted recombinant hepatitis B vaccine (Heplisav-B)

•A combination hepatitis A-hepatitis B vaccine (Twinrix)

For travelers who are not traveling for one month, many experts favor adjuvanted Heplisav-B since it is induces a robust long-lasting immune response; it is administered in two doses one month apart.

For individuals with more time before travel, alternative vaccines include Recombivax HB or Engerix-B. These are unadjuvanted vaccines administered in three intramuscular doses; the initial dose is followed by repeat doses at one and six months later. The third dose should be given ≥2 months after the second dose and ≥4 months after the first dose. In infants, the third dose should not be administered before age 24 weeks. Ideally, immunization with these vaccines should begin six months prior to travel. Alternatively, an accelerated regimen (with doses on days 0, 7, and 21) can be administered to travelers who cannot complete the full series prior to departure. Travelers who receive an accelerated regimen should receive a booster at least six months later to optimize long-term immunity. (See "Hepatitis B virus immunization in adults".)

For immunocompromised patients, adjuvanted Heplisav-B is favored by many experts, given diminished humoral immune response to unadjuvanted vaccine. Alternatively, limited data suggest that modified dosing regimens of unadjuvanted vaccine can also increase response rates. A three-dose series of Recombivax HB (40 mcg at zero, one, and six months) or a four-dose series of Engerix-B (40 mcg at zero, one, two, and six months) may be used. (See "Hepatitis B virus immunization in adults".)

The combination vaccine can be used to complete immunizations series started with monovalent hepatitis A and B vaccines [15].

Japanese encephalitis vaccine

●General principles – Japanese encephalitis (JE) is an mosquito-borne viral encephalitis endemic throughout most of Asia and parts of the western Pacific. The highest risk of JE exposure occurs in rural agricultural areas. The likelihood of JE transmission to travelers is low, but the outcome is potentially severe. (See "Japanese encephalitis".)

●Indications – JE vaccination is appropriate for travelers visiting endemic areas during periods of JE transmission [22]. Indications for JE vaccination are summarized in the table (table 2) [23]. A list of countries can be found on the CDC website.

●Contraindications and precautions – Hypersensitivity to JE virus vaccine or any component of the formulation is a contraindication to vaccination. Since licensure of JE-VC in 2009, no pattern of severe adverse systemic or neurologic adverse events observed.

●Formulations, dosing and administration

•Within the United States – Within the United States, one JE vaccine is available: an inactivated Vero cell culture-derived vaccine (JE-VC; IXIARO). JE-VC protects against all five JE virus genotypes. An inactivated mouse brain-derived vaccine (JE-MB; JE-VAX) was discontinued in 2009.

-Dosing – For adults and children ≥3 years, each dose is 0.5 mL; for children aged two months to two years of age, each dose is 0.25 mL (one-half of the supplied prefilled adult syringe) [24].

For adults 18 to 65 years of age, the primary immunization schedule for JE-VC is two doses administered intramuscularly administered on day 0 and then any time between day 7 and day 28 [15,25]. Seroprotection rates after primary vaccination approach 100 percent.

For children <18 years of age and for adults >65 years of age, the primary immunization schedule is two doses administered intramuscularly on days 0 and 28. The two-dose series should be completed at least one week prior to travel.

-Boosters – For individuals with ongoing risk, a booster (third) dose should be administered >1 year after completion of the primary series [23]. Data demonstrate seroprotection for at least six years after the booster, and antibody decay models suggest seroprotection for at least 10 years or more [26].

Data regarding the need for subsequent booster doses are not available; a booster dose at 10 years may be considered for travelers wanting to ensure prolonged protection [26].

Following previous immunization with a complete three-dose series of JE-MB or other mouse brain vaccine, booster with JE-VC may be given; data suggest JE-VC effectively boosts immunity in travelers primed with mouse brain-derived JE vaccines [27].

•Outside the United States – Outside the United States, a live attenuated YF-JE chimeric viral vaccine (IMOJEV) has been licensed in Australia and in some Asian countries as a single 0.5 mL subcutaneous dose for primary immunization of individuals ≥12 months of age.

For individuals 12 months to 17 years of age, a booster dose should be given one to two years after the first dose to provide long-term protection. For individuals ≥18 years, there is no need for a booster dose for at least five years after the first vaccination.

Since IMOJEV is a live attenuated vaccine, it should not be used in immunocompromised individuals; its safety in pregnancy has not been evaluated.

Meningococcal vaccine

●General principles – Meningococcal meningitis is a devastating bacterial infection with high mortality; epidemics occur in the "meningitis belt" of sub-Saharan Africa, which extends from Senegal to Ethiopia (figure 1). (See "Epidemiology of Neisseria meningitidis infection".).

Historically, most meningitis belt outbreaks were due to serogroup A; after local introduction of a serogroup A meningococcal vaccine (MenAfriVac) in 2010, subsequent outbreaks have been caused primarily by serogroups C and W. There is no specific travel-related risk for type B meningococcal infection.  

●Indications – Meningococcal ACWY vaccine is recommended for nonimmune travelers to the meningitis belt in Africa, especially during the dry season (December to June), as well as for health care workers (year-round). Proof of vaccination is required for travel to Mecca during the annual Hajj and Umrah pilgrimages.

Other (non-traveler) groups for whom meningococcal vaccine is warranted are outlined separately. (See "Meningococcal vaccination in children and adults", section on 'Immunization of persons at increased risk'.)

●Contraindications and precautions – Hypersensitivity to other meningococcal-containing vaccines is a contraindication to vaccination.

Immunization is safe in immunocompromised hosts and is specifically indicated for patients with deficiencies of terminal complement components or functional or anatomic asplenia. Previous Guillain-Barré syndrome is not a contraindication to vaccination.

●Formulations, dosing, and administration – Quadrivalent meningococcal conjugate vaccine formulations (MenACWY-CRM [Menveo] and MenACWY-TT [MenQuadfi]) have replaced quadrivalent meningococcal polysaccharide vaccine (MPSV4/Menomune) and MenACWY-DT (Menactra).

MenABCWY (Penbraya; Sanofi and Penmenvy; GSK) combination vaccine is an option when both MenB and MenACWY are indicated.

Menveo (MenACWY-CRM) may be administered concomitantly with serogroup B vaccine (MenB-FHbp [Trumenba] or MenB-4C [Bexsero]).

The schedules for the primary meningococcal vaccine series and for revaccination are presented separately. (See "Meningococcal vaccination in children and adults".)

Boosters are warranted every five years if travelers plan to remain in or return to endemic areas [28].

Mpox vaccine

●General principles – Mpox is a viral zoonotic that causes a rash similar to smallpox virus. Primary routes of transmission include direct contact and indirect contact through fomites; other potential routes include respiratory transmission, vertical transmission, and percutaneous inoculation. (See "Epidemiology, clinical manifestations, and diagnosis of mpox (formerly monkeypox)".)

Clade Ia (previously Congo Basin Clade) is the original mpox strain (discovered in 1970). Clade II (previously West African Clade) and Clade IIb are the causes of 2022 global outbreak and almost all current cases occurring outside of Africa. Clade Ib is the cause of ongoing outbreak (beginning in 2023) in eastern Democratic Republic of the Congo and neighboring countries, with >30,000 cases to date.  

●Indications – In September 2024, the CDC recommended the two-dose JYNNEOS vaccine series for travelers to Central and Eastern Africa (ideally at least six weeks before departure), if they anticipate sexual activity while traveling [29]. At the time of the advisory, countries with clade I mpox outbreaks included the Democratic Republic of the Congo, along with neighboring countries as such as Burundi, Central African Republic, Rwanda, and Uganda. Health care workers and responders traveling to the outbreak without sexual risk factors are not recommended for vaccination.

Other indications for mpox vaccine are discussed separately. (See "Treatment and prevention of mpox (formerly monkeypox)", section on 'Vaccination to prevent disease'.)

●Contraindications and precautions – Vaccination is contraindicated for individuals with vaccine or vaccine-component allergies.

None of the contraindications for replicating vaccinia-based vaccines (such as cardiac disease, eczema, HIV, or immunosuppression) are applicable to MVA-BN; cardiac toxicity (myocarditis or pericarditis) and other adverse effects observed with replicating vaccinia-based vaccines (eg, eczema vaccinatum, postvaccinial encephalitis, or vaccinia necrosum) have not been reported with MVA-BN.

●Formulation, dosing, and administration

•Modified vaccinia Ankara-Bavarian Nordic (MVA-BN) vaccine is a live but non-replicating smallpox and mpox vaccine (JYNNEOS in the United States, IMVANEX in the European Union, and IMVAMUNE in Canada).

•MVA-BN is administered via subcutaneous injection with a regular syringe needle; there is no need for the special bifurcated needle used for traditional replicating smallpox vaccines. Two doses (0.5 mL each) are administered four weeks apart.

•ACAM2000 – ACAM2000 is a replication-competent (live) smallpox and mpox vaccine that is not commercially available. It can be used only in select patients and is associated with more adverse events than the MVA vaccine. The FDA approved ACAM2000 for the mpox indication in 2024. No doses have been released to date from the United States Strategic National Stockpile for mpox prevention.

Rabies vaccine

●General principles – Rabies is a viral disease transmitted by dogs, bats, and other animals that leads to encephalopathy and death. Rabies is endemic in most countries of Asia, Africa, and Central and South America [15].

●Indications – Preexposure vaccination is indicated for travelers to destinations with moderate or high risk for rabies, those working with animals, and those whose travel plans may preclude timely postexposure prophylaxis.

Children are at increased risk as they are more likely than adults to play with animals and they may not reliably report exposures. A list of countries is available on the CDC website.

●Contraindications and precautions – Hypersensitivity to rabies vaccine or any component of the formulation is a contraindication to vaccination. The rabies vaccines are acceptable for use in pregnancy and for immunocompromised individuals.

●Formulations, dosing and administration

•Formulations − There are two formulations of rabies vaccine available in the United States:

-Human diploid cell vaccine (HDCV; Imovax)

-Purified chick embryo cell vaccine (PCECV; RabAvert)

Additional vaccines are available outside the United States.

•Initial regimen – The CDC and the WHO have endorsed a preexposure prophylaxis regimen consisting of two doses on days 0 and 7 [30,31]; previously, the regimen (initial and subsequent priming) consisted of three doses. The CDC and WHO recommend that preexposure prophylaxis be given intramuscularly; the WHO also endorses an intradermal regimen [31]. (See "Rabies immune globulin and vaccine".).

Preexposure vaccination does not eliminate the need for medical attention if exposure occurs, but it simplifies postexposure prophylaxis. (See "Rabies immune globulin and vaccine".)

For short-stay travelers departing in less than one week, we administer a single dose of vaccine even if the second dose is not possible; in one study including travelers age 18 to 50 years, a single rabies vaccination effectively primed an effective anamnestic response to a single booster dose (simulated postexposure prophylaxis) for at least six months [32].

•Subsequent priming regimens

-International guidelines regarding the durability of two doses of preexposure prophylaxis vary. The WHO considers two doses sufficient, whereas CDC considers two doses to be protective for three years. Individuals at risk for ongoing exposure beyond this time period should proceed in one of the following ways:

I. Check a titer during years one to three years after completing the initial regimen; boost if titer is <0.5 international units/mL.

II. Receive a third vaccine dose between 21 days and three years after completion of the initial two-dose regimen.

Thereafter, no further titers are needed, and no further vaccine doses are needed unless postexposure prophylaxis is warranted following an exposure.

•Role of postexposure vaccination − Pre-exposure immunization (priming) does not eliminate the need for postexposure administration of two booster doses spaced by three days. The approach to rabies postexposure prophylaxis is discussed separately. (See "Indications for post-exposure rabies prophylaxis".)

Tick-borne encephalitis vaccine

●General principles – Tick-borne encephalitis (TBE) is a viral infection of the central nervous system that occurs in Europe and eastern Asia [33]. The disease is primarily transmitted by ticks between April and November; transmission may also occur after ingestion of unpasteurized dairy products from infected cows, sheep, or goats. (See "Arthropod-borne encephalitides", section on 'Tick-borne encephalitis virus'.)

●Indications

•TBE vaccine is recommended for individuals who are travelling or moving to an area where TBE is endemic and will have extensive exposure to ticks because of their planned outdoor activities and itinerary. Extensive exposure can be considered based on the duration of travel and frequency of exposure and might include shorter-term (eg, <1 month) travelers with daily or frequent exposure or longer-term travelers with regular (eg, a few times a month) exposure to environments that might harbor infected ticks [34].

•TBE vaccine may be considered for individuals who are travelling or moving to an area where TBE is endemic and might engage in outdoor activities in areas where ticks are likely to be found. Consider their planned activities and itinerary and likely extent of exposure to ticks, risk factors for a poor medical outcome (eg, aged ≥60 years), and personal perception and tolerance of risk.

●Contraindications and precautions – Severe allergic reaction (eg, anaphylaxis) to any vaccine component.

●Formulations, dosing, and administration

•Formulations – TBE vaccines are available in Europe (FSME-IMMUN/Ticovac and Encepur; including Russia) and Australia [35,36].

In the United States, tick-borne encephalitis vaccine (Ticovac) for adults and children ≥1 year was approved in 2021 [34,37]. (See "Arthropod-borne encephalitides", section on 'Tick-borne encephalitis virus'.)

•Dosing and administration – For individuals ≥16 years, the dose is 0.5 mL intramuscularly. The vaccine is administered as three doses (first dose on day 0, second dose 14 days to 3 months after the first dose, third dose 5 to 12 months after the second dose). Short-stay travelers are protected a week after the second dose, but should receive the third dose if further exposure is expected [38].

For children 1 to 15 years, the dose is 0.25 mL intramuscularly. The vaccine is administered as three doses; the first two doses are administered 1 to 3 months apart, and the third dose is administered 5 to 12 months after the second dose.

A booster dose (fourth dose) may be given at least three years after completion of the primary series if ongoing exposure or re-exposure to tick-borne encephalitis virus is expected.

Typhoid vaccine

●General principles – Typhoid fever is a water and food-borne infection caused by Salmonella enterica serotype Typhi. It is prevalent in many areas of Asia, Africa, and Latin America. Drug-resistant strains of S. Typhi are increasingly prevalent globally.

●Indications – Typhoid vaccination is recommended for travelers to areas with risk of exposure to S. Typhi. Individuals at highest risk include traveling to resource-limited settings, long-term travelers, travelers visiting friends and relatives, and those traveling to South Asia.

The risk of infection increases with the duration of stay, although travelers have become ill during visits to endemic areas of less than one week. A list of countries is available on the CDC website.

●Contraindications and precautions – The oral typhoid vaccine is a live attenuated vaccine so should not be administered to individuals with immunodeficiency, acute febrile illness, or acute gastrointestinal illness. Many experts avoid its use in pregnancy and in individuals with chronic intestinal issues including irritable bowel syndrome.

●Formulations, dosing, and administration – Two typhoid vaccines are available in the United States:

•Vi polysaccharide vaccine (Typhim Vi; a parenteral vaccine), administered in a single 0.5 mL intramuscular injection (age ≥2 years). A booster dose is recommended two years later in the United States and three years later in Canada and many other countries.

•Ty21a vaccine (Vivotif; a live oral vaccine), administered as a four-dose course (days 1, 3, 5, and 7) for age ≥6 years; it is supplied as a packet of enteric-coated capsules that must be kept refrigerated.

Ty21a should not be administered within 72 hours of antibiotics [39]; it may be given with antimalarial drugs at doses used for malaria chemoprophylaxis [40]. It provides protection for five years.

For coadministration of Ty21a and oral cholera vaccine (CVD 103-HgR; Vaxchora), the first dose of oral typhoid vaccine should be administered >8 hours after administration of oral live attenuated cholera vaccine due to interference by the CVD 103-HgR buffer.

The above vaccines provide 50 to 59 percent protection against typhoid fever [41].

In addition, Vi-TT typhoid conjugate vaccine (TCV) is a parenteral vaccine available in India, Nepal, and a number of endemic locations outside the United States and Europe [42]. (See "Enteric (typhoid and paratyphoid) fever: Treatment and prevention", section on 'Vaccination'.)

Yellow fever vaccine

●General principles

•Yellow fever – Yellow fever (YF) is a mosquito-borne viral infection endemic in equatorial Africa and areas of South America, but not in Asia [15,43]. There is no specific treatment, and mortality can exceed 20 to 50 percent. Fatalities due to YF acquired by unvaccinated tourists have occurred [44-47]. (See "Yellow fever: Epidemiology, clinical manifestations, and diagnosis".)

•Vaccine characteristics – The YF vaccine (YF-Vax) is a live virus vaccine grown in chick embryos. Following vaccine administration, a low-level viremia with the vaccine virus often develops within three to seven days and persists for one to three weeks [43].

•Vaccination certificate – Some countries require proof of YF vaccination before entry, usually if the traveler is arriving from an endemic country. However, many countries with YF transmission do not have a legal requirement for vaccination; travelers to those countries need YF vaccination for their own protection.

To meet entry requirements (for countries that have them), the YF vaccination certificate is valid beginning 10 days after administration of YF vaccine for primary vaccine recipients; this corresponds to the time at which most vaccine recipients demonstrate immunity. A YF vaccination certificate for international travel is valid for the life of the recipient.

YF vaccine may be administered only through registered clinics and sites.

●Indications – Travelers age ≥9 months who are traveling to or living in areas at risk for YF transmission in South America and Africa should be vaccinated. In addition, the International Health Regulations allow countries (with or without local disease) to require proof of YF vaccination as a condition of entry for travelers arriving from certain countries, to prevent importation and indigenous transmission of YF virus. YF vaccine recommendations can be found on the WHO website and the United States Centers for Disease Control and Prevention (CDC) website .

●Major adverse events – Three well-characterized serious adverse events occur following YF vaccine administration (see "Yellow fever: Treatment and prevention", section on 'Adverse effects'):

•YF vaccine-associated neurologic disease (YEL-AND)

-Clinical manifestations – YEL-AND is a serious but rarely fatal adverse event. YEL-AND manifests as several distinct clinical syndromes, including meningoencephalitis, Guillain-Barré syndrome (GBS), acute disseminated encephalomyelitis (ADEM), and bulbar palsy. Meningoencephalitis occurs due to direct viral invasion of the central nervous system; the other syndromes are autoimmune manifestations [43].

-Incidence – The overall incidence of YEL-AND is 0.4 to 0.8 cases per 100,000 doses distributed [48].

The incidence among 60 to 69-year-olds is 1.6 cases per 100,000 doses distributed [43].

The incidence among patients ≥70 years is 1.1 to 2.3 cases per 100,000 doses distributed [43].

The incidence among very young infants has been estimated to be 50 to 400 cases per 100,000 population.

These estimates are likely low given underreporting.

•YF vaccine-associated viscerotropic disease (YEL-AVD)

-Clinical manifestations – YEL-AVD mimics naturally acquired YF disease, with proliferation and dissemination of the vaccine virus throughout the host tissues. This syndrome was first reported in 2001, and >100 cases have been described worldwide [15,49]. The median time from vaccination to symptom onset is three days (range one to eight days); death has occurred in 65 percent of cases. All known cases of YEL-AVD have occurred following a recipient's first YF vaccination, with no reported cases following booster doses.

-Incidence – The overall incidence of YEL-AVD is 0.3 to 0.4 cases per 100,000 doses distributed [48].

The incidence among 60 to 69-year-olds is 1.0 to 1.1 cases per 100,000 doses distributed [43].

The incidence among patients ≥70 years is 2.3 to 3.2 cases per 100,000 doses distributed [43].

•Immediate hypersensitivity or anaphylactic reactions – These are uncommon (1.4 per 100,000 doses administered) and principally occur among persons with histories of allergies to egg or other substances [48,50]. The YF vaccine package insert contains a desensitization regimen that can be considered. (See "Allergic reactions to vaccines".)

●Contraindications – YF vaccine is a live attenuated vaccine; therefore, it should not be given to the following individuals:

•Patients with primary immunodeficiencies

•Transplant recipients

•Patients on immunosuppressive and immunomodulatory therapies

•Patients with human immunodeficiency virus (HIV) whose CD4 count is <200/mL

•Patients with history of thymus disease or thymectomy

•Individuals age <6 months

•Individuals with allergy to a vaccine component

For individuals planning travel to an area for which YF vaccine is recommended to avoid risk of infection in the unvaccinated traveler, serious consideration to a change in itinerary should be advised. For situations in which YF vaccine administration is contraindicated but YF vaccine documentation must be presented to international customs officials according to International Health Regulations, a Medical Letter of Waiver can be provided; however, this does not guarantee entry to all countries with yellow fever vaccine entry requirements.

●Precautions

•By age – Age-related for precautions for YF vaccination include:

-Travelers ≥60 years of age

-Infants aged 6 to 8 months

For these patients, the risk of severe illness and death due to YF infection should be balanced against the risk of serious vaccine adverse effects [51].

•Pregnancy – Pregnancy is a precaution for YF vaccine administration (in contrast with most other live vaccines, which are contraindicated in pregnancy). If travel is unavoidable and the risks for YF virus exposure are felt to outweigh the risks of vaccination, a pregnant patient should be vaccinated. If the risks for vaccination are felt to outweigh the risks for YF virus exposure, pregnant patients should be issued a medical waiver to fulfill any international health regulation requirement [43].

●Dosing and administration

•Dosing

-Standard dosing consists of a single 0.5 mL subcutaneous injection.

-Booster vaccination - A single primary dose of yellow fever vaccine is adequate for most travelers [52]. Issues related to yellow fever booster vaccination for travelers are discussed separately. (See "Yellow fever: Treatment and prevention", section on 'Travelers'.)

-Fractional dosing (a single 0.1 mL [one-fifth of the normal dose] subcutaneous injection) has been used in emergency situations to control outbreaks; thus far, data are complex and insufficient for most national and international authorities to support the use of fractional dosing in travelers [53]. A fractional dose does not meet the criteria for proof of vaccination to be documented on an International Certificate of Vaccination or Prophylaxis. (See "Yellow fever: Treatment and prevention", section on 'Fractional vaccine dosing'.).

•Administration – YF vaccine should be administered either simultaneously or four weeks apart from other live injectable viral vaccines. Other inactivated vaccines and oral live vaccines can be administered either simultaneously or at any time before or after YF vaccination.

Vaccination must occur at least 10 days before entry into a country with a yellow fever entry requirement; travelers are not considered immune until 10 days after vaccination.

Vaccine recipients should be instructed to report symptoms of any kind within one week of vaccination. Any vaccine recipient with flu-like or febrile illnesses should return for clinical evaluation.

ROUTINE IMMUNIZATIONS — 

The pretravel visit provides an opportunity to ensure that routine immunizations (including COVID, influenza, MMR [measles, mumps, and rubella], poliovirus, and Tdap [tetanus, diphtheria, and pertussis]) are current, as discussed in the following sections.

COVID vaccine — Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the cause of coronavirus disease 2019 (COVID-19), spreads via respiratory transmission. Travelers should be up-to-date with COVID-19 vaccinations before travel. Due to the rapid waning of protection after a dose of COVID vaccine, travelers may consider obtaining booster doses within a few months prior to travel, if feasible. Formulations and additional guidance are discussed further separately (see "COVID-19: Vaccines").

Influenza vaccine — Travelers likely play an important role in global spread of influenza [1]. The viruses circulate predominantly in the Northern Hemisphere from October through March and in the Southern Hemisphere from April through September; in the tropics they circulate year-round. Infection may be acquired outside of a traveler's home epidemic season.

Influenza vaccination is appropriate for all travelers to destinations during a time of influenza transmission. Formulations and additional guidance are discussed further separately. (See "Seasonal influenza vaccination in adults" and "Seasonal influenza in children: Prevention with vaccines", section on 'Travelers'.)

Measles, mumps, and rubella vaccine (MMR)

●General principles – Measles, mumps, and rubella are contagious viral illnesses that occur worldwide. Measles is characterized by fever, cough, coryza, and conjunctivitis, followed by exanthem; complications include pneumonia and encephalitis. Mumps causes an acute illness characterized by parotid swelling; complications include orchitis, oophoritis, meningitis, and encephalitis. Rubella causes a mild illness with characteristic rash; it is generally a self-limiting illness in children but can have devastating effects on the fetus when acquired during pregnancy.

Many international travelers are inadequately vaccinated against these infections, and outbreaks have been associated with imported infection [54].

●Indications – All travelers are at risk for measles and mumps infection (regardless of destination). The pretravel visit is an important opportunity to reduce the likelihood of measles transmission [54,55].

●Contraindications and precautions – MMR is a live attenuated virus vaccine; it should not be given to pregnant or immunocompromised individuals.

●Administration – Unless the vaccine is contraindicated, all international travelers older than 12 months require two doses of MMR vaccine one month apart, or evidence of immunity.

•Children – Children traveling outside the United States should receive MMR vaccination sooner than the standard immunization schedule. Prior to departure, children 12 months of age or older should have received two doses of MMR vaccine separated by at least 28 days, with the first dose administered on or after the first birthday. Children aged 6 to 11 months should receive one dose of MMR before departure. (See "Measles, mumps, and rubella immunization in infants, children, and adolescents", section on 'International travel and outbreaks'.)

•Adults – MMR vaccination for adults is indicated for individuals born in 1957 or later in the United States (born in 1970 or later in Canada; born in 1966 or later in Australia) without evidence of immunity or without evidence of two doses of an adequate live vaccine at any time after age 12 months.

Individuals born before 1957 in the United States are presumed to be immune (exceptions include health care workers and women of childbearing age). Nonetheless, for unvaccinated individuals without other evidence of immunity who were born before 1957 (in the United States) and are traveling for purposes of health care or humanitarian work (potentially entailing close contact with ill individuals), two doses of MMR vaccine spaced by one month should be considered. (See "Measles, mumps, and rubella immunization in adults".)

Poliovirus vaccine

●General principles – Poliomyelitis is a viral infection transmitted via the fecal-oral route that can affect the central nervous system, leading to muscle weakness and flaccid paralysis.

As of 2024, wild-type polio viruses persist in two countries: Pakistan and Afghanistan. Vaccine-derived polio viruses circulate in more than 20 countries in Asia and Africa. Information about recent cases can be found on the Global Polio Eradication Initiative website. (See "Global poliomyelitis eradication".)

Some countries require proof of recent polio vaccination for travelers arriving from areas with circulating wild-type or vaccine-derived polio viruses. For information on the status of polio vaccine recommendations, refer to the CDC website.

●Indications – All travelers should have received an age-appropriate primary series of polio vaccination.

The CDC recommends that travelers ≥18 years of age who are traveling to areas with risk for poliomyelitis receive a one-time adult booster vaccination.

The WHO recommends that residents and long-term visitors (≥4 weeks) to these areas show proof of polio vaccination before exiting; such immunity is defined as receipt of a polio vaccine within 12 months prior to exiting [56].

●Formulations – There are two types of polio vaccine: an oral polio vaccine (OPV), containing live attenuated polioviruses, and an inactivated polio vaccine (IPV); only IPV is available in the United States.

Poliovirus vaccination is discussed in further separately. (See "Poliovirus vaccination".)

Tetanus, diphtheria, and pertussis vaccine (Tdap)

●General principles – Tetanus is a nervous system disorder characterized by muscle spasms caused by the toxin-producing anaerobe Clostridium tetani; infection typically occurs following traumatic injury. Diphtheria is caused by the gram-positive bacillus Corynebacterium diphtheriae; infection may lead to respiratory or cutaneous disease. Pertussis is a communicable respiratory infection caused by Bordetella pertussis.

●Indications – All travelers should have received an age-appropriate primary vaccination series. All adults should receive at least one tetanus, diphtheria, and pertussis (Tdap) vaccination, followed by a Tdap (ideally) or Td booster if more than 10 years have elapsed. Pregnant individuals should receive a Tdap vaccine during each pregnancy.

Tdap and Td vaccination are discussed further separately. (See "Pertussis infection in adolescents and adults: Treatment and prevention", section on 'Vaccination' and "Tetanus-diphtheria toxoid vaccination in adults".)

Other vaccines — A pretravel health assessment is an opportunity to ensure that an individual has received all appropriate vaccinations (figure 2). These may include:

●Pneumococcal vaccine (See "Pneumococcal vaccination in adults".)

●Respiratory syncytial virus (RSV) vaccine (See "Respiratory syncytial virus infection in adults", section on 'Vaccination'.)

●Varicella vaccine (See "Vaccination for the prevention of chickenpox (primary varicella infection)".)

●Zoster vaccine (See "Vaccination for the prevention of shingles (herpes zoster) in adults".)

General information on immunizations is presented separately. (See "Standard immunizations for nonpregnant adults" and "Immunizations during pregnancy" and "Standard immunizations for children and adolescents: Overview".)

IMMUNOCOMPROMISED PATIENTS — 

In general, severely immunocompromised patients should not receive live vaccines.

Live parenteral vaccines include:

●Chikungunya vaccine

●Dengue vaccine (Qdenga; available outside the United States)

●Live Japanese encephalitis vaccine (IMOJEV; available outside the United States)

●Measles, mumps, and rubella (MMR)

●Varicella vaccine

●Yellow fever vaccine

●Zoster vaccine live (ZVL; available outside the United States)

●Live oral or nasal vaccines include:

●Oral cholera vaccine (Vaxchora)

●Nasal influenza vaccine

●Oral polio vaccine (OPV; available outside the United States)

●Oral typhoid vaccine

Inactivated vaccines include:

●COVID-19 vaccines

●Hepatitis A and B vaccines

●Inactivated influenza vaccine

●Inactivated Japanese encephalitis vaccine (IXIARO)

●Meningococcal vaccines

●Mpox (Jynneos) vaccine (live but non-replicating)

●Pneumococcal vaccines

●Inactivated polio vaccine (IPV)

●Rabies vaccine

●Respiratory syncytial virus (RSV) vaccine

●Tdap (tetanus, diphtheria, and pertussis) and Td (tetanus, diphtheria) vaccine

●Tickborne encephalitis vaccine

●Parenteral typhoid vaccine

●Recombinant zoster vaccine (RZV)

Issues related to immunizations in immunocompromised patients are discussed in detail separately, as are issues related to immunizations in individuals with HIV infection and in pregnancy. (See "Travel advice for immunocompromised hosts" and "Immunizations in patients with inborn errors of immunity" and "Immunizations in persons with HIV" and "Immunizations during pregnancy".)

SOCIETY GUIDELINE LINKS — 

Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Rabies" and "Society guideline links: Travel medicine".)

INFORMATION FOR PATIENTS — 

UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Vaccines for travel (The Basics)" and "Patient education: Vaccines for adults (The Basics)" and "Patient education: What you should know about vaccines (The Basics)")

●Beyond the Basics topic (see "Patient education: General travel advice (Beyond the Basics)")

SUMMARY AND RECOMMENDATIONS

●General principles – Immunizations for travelers may be divided into the following categories:

•Travel immunizations – Travel immunizations include (table 1) (see 'Immunizations for travel' above):

-Immunization required under international health regulations (eg, yellow fever)

-Immunization to reduce risk of infection guided by travel plans (destination[s] and activities)

Guidance for destination-specific immunizations can be found at www.cdc.gov/travel.

•Routine immunizations – Pretravel visits offer an opportunity to update routine vaccinations for travelers. (See 'Routine immunizations' above.).

●Review medical history and travel plans – Immunization needs are based on the traveler's medical history, travel plans, and prior immunizations. Guidance for destination-specific immunizations can be found at www.cdc.gov/travel. (See "Travel advice", section on 'Review medical history and travel plans'.)

●Immunizations for travel – Vaccine indications, contraindications, precautions, formulations, dosing, and administration are described above. (See 'Immunizations for travel' above.)

●Vaccine coadministration – Any combination of vaccines can be administered at a single appointment. Additional guidance regarding administration of live vaccines is discussed above. (See 'Vaccine coadministration' above.)

●Immunocompromised patients – In general, severely immunocompromised patients should not receive live vaccines. These include chikungunya vaccine, oral cholera vaccine, nasal influenza vaccine, MMR, oral polio vaccine (OPV), oral typhoid vaccine, varicella vaccine, yellow fever vaccine, and zoster vaccine live (ZVL). (See 'Immunocompromised patients' above.)