Immunizations for Travel

Published on 14/03/2015 by admin

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Last modified 22/04/2025

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Immunizations for Travel

Immunizations may be divided into three categories: routine, recommended, and required. The international traveler should have all current immunizations recorded in the World Health Organization (WHO) International Certificate of Vaccination. This yellow document is recognized worldwide and has a special page for official validation after receiving yellow fever vaccine.

The Centers for Disease Control and Prevention (CDC) Travelers’ Health website provides resources for locating a pretravel vaccination clinic. The site also provides links to state health departments and the Yellow Fever Vaccination Clinic Registry that lists facilities approved to provide yellow fever vaccinations (http://wwwnc.cdc.gov/travel/contentTravelClinics.aspx).

The CDC provides travel health information to address the many different health risks a traveler may face with electronic access through its website (http://www.cdc.gov/travel). This site offers information to assist travelers in deciding the vaccines, medications, and other measures necessary to prevent illness and injury during international travel. CDC Health Information for International Travel (“The Yellow Book”) is an excellent resource for travel health and is available in a searchable online version on the CDC Traveler’s Health website at http://www.cdc.gov/yellowbook.

Routine Immunizations

Routine immunizations are those customarily given in childhood and updated in adult life. The vaccines currently recommended in childhood include those against tetanus, diphtheria, pertussis, varicella, measles-mumps-rubella, poliovirus, Haemophilus influenzae type b, hepatitis A, and hepatitis B. The recommended immunization schedules for persons ages 0 to 6 years and 7 to 18 years are published each year as approved by the Advisory Committee on Immunization Practices (http://www.cdc.gov/vaccines/recs/acip), the American Academy of Pediatrics (http://www.aap.org), and the American Academy of Family Physicians (http://www.aafp.org). A complete list of routine childhood and adult immunization recommendations and immunization schedules can be found at http://www.cdc.gov/vaccines/schedules/index.html.

Recommendations for immunization against influenza, meningococcal disease, and pneumococcal pneumonia are based on underlying health and age. A catch-up immunization schedule is available for persons ages 4 months to 18 years who begin their immunizations late or who are more than 1 month behind schedule with any particular immunization.

1. Diphtheria, Tetanus, and Pertussis: Primary immunization in young children is accomplished with a combination vaccine containing acellular pertussis antigen. The tetanus and diphtheria toxoids (Td) vaccine classically used for booster doses in older children and adults has no pertussis component and a lower dose of diphtheria antigen. Absence of a pertussis booster for adults has led to waning immunity and susceptibility to pertussis. Booster doses of Td vaccine given at 10-year intervals are recommended to maintain immunity. For adventure and other travelers to remote locations who might sustain open wounds and be unable to safely obtain a tetanus booster, a Td booster could be given after 5 years. Particularly for travelers to areas of the world where diphtheria remains a risk (e.g., most countries of Africa, Asia, and the Middle East, countries of the former Soviet Union, and focal areas of Latin America), care must be taken to recognize that the last “tetanus” booster might really have been tetanus toxoid alone without the diphtheria component. If the person has no record or recollection of immunization, it is advisable to obtain this vaccine before traveling. If there is any doubt about whether or not an adult received the primary series, three doses of Td should be administered; the first dose and second dose should be separated by 4 weeks and the third dose should be given 6 to 12 months later.

    Combination vaccines with acellular pertussis and adult dose of diphtheria (tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis [Tdap]) are now approved for use in adolescents (in place of the regularly scheduled dose of Td at ages 11 to 18) and adults in the United States. For all adults, regardless of travel, who have not yet received a dose of Tdap, a one-time dose of Tdap should replace the next dose of Td. Tdap is given only once in a lifetime to cover for pertussis in the adult. Td does not have the pertussis component.

2. Measles, mumps, and rubella: Travelers to developing countries are at risk for acquiring measles. If travelers have received two doses of measles vaccine, usually given in childhood as the measles-mumps- rubella (MMR) vaccine, they are protected. Persons born after 1956 should receive a second dose of measles vaccine, which is now available only as MMR. Adults who have not received two doses of the measles vaccine and who do not have a documented history of infection or immunity should receive two doses of MMR vaccine separated by at least 28 days. MMR vaccine is a live attenuated virus preparation. It is contraindicated in pregnancy and in immunocompromised persons.

3. Poliovirus: Poliomyelitis vaccine is usually not boosted after childhood in the United States except for anticipated high-risk exposure through work or travel to areas where polio is endemic. An inactivated (killed) virus polio vaccine (IPV) regimen is recommended for a primary immunization series given before 18 years of age. IPV is also recommended for booster doses in people 18 years and older because of a higher risk of complications associated with the live oral vaccine in older individuals. Polio has been nearly eradicated worldwide, except for India. All traveling adults should have received a primary course of the polio vaccine.

4. H. influenzae type B: Immunization is acquired in childhood. The risk for invasive H. influenzae disease, including meningitis, is greatest in children younger than 7 years old, and the infection is common among children in the developing world. Traveling children should be kept up-to-date according to standard pediatric vaccination schedules.

5. Influenza: Influenza vaccine is recommended for all health care workers and for international travelers because prolonged air travel and exposure to crowded or extreme environments create a predisposition to infection. Other considerations are based on conventional recommendations regarding underlying health and age (e.g., all people older than 65 years and those with chronic lung, heart, or kidney disease or with impaired immunity). The current influenza vaccine is not protective against avian influenza A (H5N1), which has caused outbreaks, including fatalities, in Southeast Asia and China. Travelers to locations where avian influenza might be transmitted should avoid visits to markets or farms or other activities that might bring them into close contact with fowl.

6. Pneumococcal: Pneumococcal vaccine polyvalent is administered intramuscularly as a 0.5-mL single dose and is recommended for all adults 65 years or older (this recommendation may be lowered to 50 years of age) and in younger individuals with conditions that increase the risk for invasive pneumococcal disease. Specific indications for pneumococcal vaccination in adults younger than 65 years include the following:

Pneumococcal conjugate vaccine is routinely recommended for infants younger than 2 years to prevent pneumococcal disease, including meningitis and septicemia.

Recommended Vaccines for Travelers (Table 49-1)

Recommended vaccines are those that are not routinely given during childhood in the United States but are advised for travelers based on their travel health risk assessment. Vaccines in this category include those for hepatitis A and B, typhoid fever, meningococcal meningitis, Japanese encephalitis virus, rabies, tick-borne encephalitis, varicella zoster virus (VZV), influenza, and bacillus Calmette-Guérin (BCG). Some vaccines have become routine in children (e.g., hepatitis B since 1991, and hepatitis A more recently in the United States). Influenza vaccine is often but not routinely used in children; each year it is recommended for many travelers. Although BCG vaccination is used in children in the developing world, it is not used in U.S. children.

Hepatitis A

Hepatitis A virus (HAV) infection is the most common vaccine-preventable disease in international travelers to the developing world. In the absence of vaccination, HAV infection occurs in 1 to 10 persons per 1000 travelers at risk during 2 to 3 weeks of travel. Risk is high even among those residing in “first-class” accommodations. Adventure travelers who venture off usual tourist routes may be at increased risk compared with other groups of travelers. Although HAV infection is asymptomatic in young children and self-limited in most adults, it causes greater than 2% mortality in infected adults older than age 40 years, considerable morbidity during travel, and lost productivity after travel. Vaccination against HAV should be considered for all travelers to regions where sanitation and hygiene are poor.

Two hepatitis A inactivated viral vaccines are approved in the United States: Havrix and VAQTA. Both vaccines are safe, efficacious, and produce long-lasting immunity. Each vaccine is given by intramuscular injection into the deltoid muscle. A single dose of hepatitis A vaccine affords adequate protection by 7 to 10 days following vaccination. After two full doses separated by 6 to 12 months, protection is likely life long, so booster doses are not recommended in immunocompetent travelers. Travelers who fail to receive their second dose of HAV vaccine within 6 to 12 months should simply receive one full dose of monovalent vaccine with the anticipation of lifelong immunity. Protective antibody levels have been produced even when second doses were given 8 years after the first dose.

Although indirect evidence in humans suggest that immunization with monovalent vaccine immediately before travel obviates the need for serum immune globulin, some authorities continue to advocate a dose of serum immune globulin if HAV vaccination cannot be given sooner than 2 weeks before travel.

Hepatitis B

Hepatitis B vaccine is now recommended as a routine immunization for children in the United States. Only adults at high risk need to receive immunization, but consideration should be given to immunizing all U.S. adults, regardless of travel. Immunization should be considered for travelers staying 6 or more months in Asia, Africa, or other endemic areas. In addition, immunization is recommended for travelers at high risk, such as medical workers or those anticipating sexual contact with locals in endemic areas. Two vaccines are available: Recombivax HB and Engerix-B. Both are recombinant vaccines containing inactivated virus and are felt to be interchangeable.

Vaccine Summary

Although a highly accelerated 3-week schedule is not approved, literature supports dosing at 0, 7, and 21 days with a 12-month booster. This regimen affords 65% protection at the end of 1 month and is an attractive option for at-risk travelers who plan to depart in the next 3 to 4 weeks.

A combined hepatitis A and hepatitis B vaccine is now available and is dosed at 0, 1, and 6 months. Because a smaller dose of HAV antigen is used in this preparation, travelers must receive their second dose before travel for reliable protection. Literature also supports a highly accelerated 3-week dosing regimen with a 12-month booster.

Meningococcus

Vaccine protection against meningococcal meningitis is recommended for long-term travelers to the sub-Saharan “meningitis belt” of Africa. Short-term travelers to this region should receive vaccine if they will travel during the dry season (December to June) or have extensive contact with local people. Meningococcal vaccine is required for travel to Saudi Arabia during the time of the annual Hajj and Umrah religious pilgrimages. Regardless of travel, the classic recommendation has been that young adults who will live in school dormitories, persons with complement deficiencies, persons who will have prolonged contact with a local population such as in a refugee camp, and persons with surgical or functional asplenia should be vaccinated. Travelers to regions where outbreaks are occurring should be vaccinated. Check the CDC website (http://www.cdc.gov/travel) to determine where epidemic disease is occurring.

The quadrivalent meningococcal polysaccharide vaccine induces immunity against serogroups A, C, Y, and W-135. A single dose appears to provide immunity for 5 years. A single-dose quadrivalent meningococcal polysaccharide-protein conjugate vaccine is the preferred vaccine for persons older than 2 years, with a booster recommended every 5 years for ongoing risk. However, neither vaccine provides immunity against serogroup B. Travelers who have previously been vaccinated with polysaccharide vaccine and need revaccination should receive conjugate vaccine.

Japanese Encephalitis Virus

Japanese encephalitis (JE) is a mosquito-transmitted viral infection prevalent in Asia and Southeast Asia. Transmission is year-round in tropical and subtropical areas and during the late spring, summer, and early fall in temperate climates. JE virus is not considered a risk for short-term travelers visiting the usual tourist destinations in urban and developed resort areas.

Risk for infection can be greatly decreased by personal protective measures that prevent mosquito bites. For visitors to rural areas during the transmission season, the estimated risk for JE during a 1-month period is 1 : 5000, so vaccination should probably be offered to both long- and short-term visitors to rural areas during transmission season, particularly when mosquito exposure might be intense and rice and pig farming occurs nearby.

The standard schedule for the inactivated viral vaccine (mouse brain preparation) has been doses injected at 0, 7, and 30 days. An accelerated schedule of doses at 0, 7, and 14 days results in a lower rate of seroconversion. When risk for exposure continues, a booster dose of vaccine may be given every 2 to 3 years.

Adverse reactions to the mouse brain preparation of JE vaccine include local pain and swelling at the injection site in about 20% of recipients, systemic symptoms (fever, headache, malaise, rash) in about 10%, and hypersensitivity reactions at a rate of 0.1 to 5 per 1000 administrations. The hypersensitivity reactions can rarely be fatal and may occur immediately or with delays of up to 2 weeks. Limited data suggest that persons who have had urticarial reactions to hymenoptera envenomation and to other stimuli might be at greater risk for JE vaccine–induced hypersensitivity reactions. JE vaccine recipients should be directly observed for 30 minutes after injection and should not travel until 10 days after their last dose because of the risk for delayed adverse reactions. A recently approved non–mouse brain vaccine appears considerably safer and as effective as the older vaccine. This new vaccine requires only two doses, but in the United States it is restricted to adults older than age 17 years.

Tick-Borne Encephalitis

Tick-borne encephalitis is a viral disease transmitted predominately by the bites of Ixodes ticks during the spring and summer months in rural forested areas of Central and Eastern Europe, Scandinavia, Siberia, and northern Japan. Infection can also occur after ingestion of unpasteurized dairy products from infected cows, goats, or sheep.

Two inactivated vaccines (Encepur and FSME-Immun) are available in Canada and Europe, but not in the United States. The standard dosing regimen is three doses given over a year. Accelerated schedules exist, but doses would likely need to be administered in the destination country. Whereas expatriates can consider obtaining vaccine at their new location, it is much more practical for most travelers to at-risk areas to use stringent tick-bite precautions (using repellents and residual insecticides, wearing protective clothing, and performing careful tick checks) and to avoid unpasteurized dairy products.

Tuberculosis (BCG Vaccine)

BCG vaccine is widely used worldwide for childhood immunization against tuberculosis. In the United States the CDC does not routinely recommend BCG. No consensus exists on the efficacy of BCG vaccine, but the vaccine is approved for use in children who will live where tuberculosis is prevalent or where exposure to adults with active or recently arrested tuberculosis is likely. It is also recommended for children of infected mothers. Vaccination may be appropriate for health care personnel who have negative results of purified protein derivative (PPD) skin tests and who are going to work in areas of high endemic prevalence and have limited access to medical diagnosis and treatment.

Vaccine Summary

1. Like other live attenuated vaccines, BCG vaccine is contraindicated in persons with immunosuppression caused by congenital conditions, chemotherapy, radiation therapy, HIV infection, or another condition resulting in impaired immune response. Pregnancy is considered a relative contraindication.

2. Epidemiologic data suggest that the vaccine may be more useful in protecting children from disseminated extrapulmonary complications of tuberculosis than in protecting adults from primary pulmonary infection.

3. Occasionally children in families going abroad for extended residence are requested by the receiving country to provide proof of BCG vaccination to qualify for a visa.

4. A BCG vaccine is commercially available in the United States and is approved by the American Academy of Pediatrics Committee on Infectious Diseases for use in children traveling to live in areas in which tuberculosis is prevalent or there is a likelihood of exposure to adults with active or recently arrested tuberculosis.

5. Persons immunized with BCG vaccine test positive on PPD skin tests for many years afterward, regardless of the degree of protection conferred by the vaccine.

Required Travel Vaccines

Yellow Fever

Yellow fever is a viral infection transmitted by Aedes aegypti mosquitoes in equatorial South America and Africa. The vaccine for yellow fever is highly immunoprotective. Several countries require proof of yellow fever vaccine before entry. The CDC recommends consideration of yellow fever vaccine before travel in countries at risk for yellow fever virus transmission, listed in Table 49-2, and vaccination is required for entry into the countries listed in Table 49-3.

Table 49-2

Countries With Risk for Yellow Fever Virus Transmission

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From Centers for Disease Control and Prevention: http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-related-to-travel/yellow-fever.htm. Courtesy Centers for Disease Control and Prevention.

Vaccine Summary

1. The vaccine strain is an attenuated live virus and well tolerated.

2. It is administered as a single injection.

3. Significant antibody levels are achieved in more than 95% of persons vaccinated.

4. Booster interval is every 10 years, although persistent antibody titers have been detected 30 to 40 years after vaccination.

5. The vaccine is not recommended for infants younger than 9 months because of postvaccination encephalitis.

6. It is also not recommended during pregnancy unless the risk for yellow fever is thought to be greater than the risk for adverse effects from the vaccine.

7. Other contraindications are immunosuppression or a history of severe allergy to eggs.

8. Vaccine-associated viscerotropic disease has been reported in a small number of first-time recipients of yellow fever vaccine. This may be associated with thymic dysfunction and/or age older than 60 years.

9. Another method for reducing the risk for yellow fever (or any mosquito-borne disease) is liberal use of mosquito repellent and netting in endemic areas.

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