Vaccine Recommendations for Infants and Children

Each traveler needs to be fully up to date with routine childhood vaccinations because diseases covered by these vaccines that are now rare or nonexistent in the United States are still common in other areas of the world. The recommended childhood and adolescent immunization schedule is depicted in Table 7–1. Table 7–2 depicts the catch-up schedule for children and adolescents who start their vaccination schedule late or who are >1 month behind. This table also describes the recommended minimal intervals between doses for children who need to be vaccinated on an accelerated schedule, which is sometimes required for international travel. Vaccination against yellow fever is required for travel to some countries (see Yellow Fever Vaccine Requirements and Information on Malaria Risk and Prophylaxis, by Country). Recommendations for other vaccines and immunobiologics depend on the area of travel and health status of traveler and include Hepatitis A vaccine or immune globulin and vaccinations for typhoid, meningitis, Japanese encephalitis, rabies, and influenza. Administration of these vaccines should not interfere with or postpone administration of any of the recommended childhood immunizations. If necessary, some portions of the vaccine schedule can be accelerated so that as many vaccines as possible can be given before departure. In children with chronic illnesses, decisions regarding vaccinations should be made in cooperation with their personal physicians.

Modifying the Immunization Schedule for Inadequately Immunized Infants and Younger Children before International Travel

Factors influencing recommendations for the age at which a vaccine is administered include the age-specific risks of the disease and its complications, the ability of people of a given age to respond to the vaccine, and the potential interference with the immune response by passively transferred maternal antibody. Vaccines are recommended for the youngest age group at risk for developing the disease whose members are known to develop an adequate antibody response to vaccination.

The routine immunization recommendations and schedules for infants and children in the United States do not provide specific guidelines for infants and young children who will travel internationally before the age when specific vaccines and toxoids are routinely recommended. The following section provides additional guidance for active and passive immunization of such infants and children. Additional information about all the diseases and vaccines mentioned below can be found in Chapter 3 (Specific Recommendations for Vaccinations and Disease Prevention).

Routine Infant and Childhood Vaccine-Preventable Diseases

Diphtheria and Tetanus Toxoid and Pertussis Vaccine

Diphtheria is an endemic disease in many low-income countries and has been found in the independent countries of the former Soviet Union. Tetanus occurs worldwide.

Pertussis is common in resource-poor countries and in other areas where pertussis immunization levels are low. Infants and children leaving the United States should be as well immunized as possible. Optimum protection against diphtheria, tetanus, and pertussis in the first year of life is achieved with three doses of diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP), the first administered when the infant is 6–8 weeks of age and the next two at 4- to 8-week intervals. A fourth dose of DTaP should be administered 6–12 months after the third dose when the infant is 15–18 months of age. A fifth (booster) dose is recommended when the child is 4–6 years of age. The fifth dose is not necessary if the fourth dose in the primary series was given after the child's fourth birthday.

Two doses of DTaP received at intervals at least 4 weeks apart can provide some protection; however, a single dose offers little protective benefit. Parents should be informed that infants and children who have not received at least three doses of DTaP might not be fully protected from pertussis. For infants and children <7 years of age, if an accelerated schedule is required to complete the series before travel, the schedule may be started as soon as the infant is 6 weeks of age, with the second and third doses given 4 weeks after each preceding dose. The fourth dose should not be given before the infant is 12 months of age and should be separated from the third dose by at least 6 months. The fifth (booster) dose should not be given before the child is 4 years of age.

Measles Vaccine

Measles is an endemic disease in many low-income countries and in other countries where measles immunization levels are low. Because the risk of contracting measles in many countries is greater than in the United States, infants and children should be as well protected as possible before traveling. Infants and children who travel or live abroad should be vaccinated at an earlier age than is recommended for infants and children who remain in the United States. Before their departure from the United States, infants and children of 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. Infants 6–11 months of age should receive a dose of monovalent measles vaccine before departure. If monovalent measles vaccine is not available, no specific contraindication exists to administering MMR to infants 6–11 months of age. However, because the risk for serious disease from either mumps or rubella infection among infants is relatively low and because infants <12 months of age are less likely to develop serologic evidence of immunity when vaccinated with MMR antigens than are older infants and children, mumps and rubella vaccines generally are administered only to infants and children 12 months of age or older. Infants administered monovalent measles vaccine or MMR before their first birthday should be considered potentially susceptible to all three diseases and should be revaccinated with two doses of MMR, the first of which should be administered when the infant is 12–15 months of age (12 months if the infant remains in an area where disease risk is high) and the second at least 28 days later.

Parents who travel or live abroad with infants <12 months of age should have acceptable evidence of immunity to rubella and mumps, as well as measles, so they will not become infected if their infants contract these diseases. An infant <6 months of age is usually protected against measles, mumps, and rubella by maternally derived antibodies and ordinarily does not need additional protection unless the mother is diagnosed with measles.

Mumps and Rubella Vaccine(s)

Because the risk of serious disease from infection with either mumps or rubella in infants is low, mumps and rubella vaccine(s) generally should not be administered to infants <12 months of age unless measles vaccine is indicated and single-antigen measles vaccine is not available. However, parents of an infant <12 months of age should be immune to mumps and rubella so they will not expose the infant or become infected if the infant becomes ill.

Varicella Vaccine

Varicella (chickenpox) is an endemic disease throughout the world. A single dose of varicella vaccine should be administered to all susceptible infants and children without contraindications at 12 months of age or older. Infants and children who have a reliable history of having had chickenpox do not need to be vaccinated. Infants <12 months of age are generally protected from varicella because of passive maternal antibody.

Polio Vaccine

Because OPV is no longer used for routine immunization in the United States, all infants and children should receive four doses of IPV at 2, 4, and 6–18 months and 4–6 years of age. If accelerated protection is needed, the minimum interval between doses should be 4 weeks, although the preferred interval between the second and third doses is 2 months. Infants and children who have initiated the poliovirus vaccination series with one or more doses of OPV should receive IPV to complete the series.

Haemophilus influenzae Type b Conjugate Vaccine

Haemophilus influenzae type b (Hib) is an endemic disease worldwide. Risk of acquiring the disease might be higher in resource-poor countries than in the United States. In the United States, three types of Hib conjugate vaccines are available. One Hib conjugate vaccine for infants is also available as a combined DTaP-Hib vaccine. Routine Hib vaccination beginning at 2 months of age is recommended for all U.S. children. The first dose may be given when an infant is as young as 6 weeks of age. Hib vaccine should never be given to an infant <6 weeks of age. A primary series consists of two or three doses (depending on the type of vaccine used) separated by 4–8 weeks. A booster dose is recommended when the infant is 12–15 months of age.

If Hib vaccination is started when the infant or child is 7 months of age or older, fewer doses may be required. If different brands of vaccine are administered, a total of three doses of Hib conjugate vaccine completes the primary series. After completion of the primary infant vaccination series, any of the licensed Hib conjugate vaccines may be used for the booster dose when the infant is 12–15 months of age.

Infants and children should have optimal protection before traveling. If previously unvaccinated, infants <15 months of age should ideally receive at least two vaccine doses before travel. An interval as short as 4 weeks between these two doses is acceptable. Unvaccinated infants and children 15–59 months of age should receive a single dose of Hib vaccine.

Hepatitis B Vaccine

Hepatitis B vaccine is recommended for all infants, with the first dose administered in the first 2 months of life, preferably at birth. Infants and young children who have not previously been vaccinated and who are traveling to areas with intermediate and high hepatitis B virus (HBV) endemicity are at risk if they are directly exposed to blood from the local population. Circumstances in which HBV transmission could occur include receipt of blood transfusions not screened for HBV surface antigen (HBsAg), exposure to unsterilized needles (or other medical or dental equipment) in local health facilities, or continuous close contact with local residents who have open skin lesions (impetigo, scabies, or scratched insect bites). Such exposures are most likely to occur if an infant or a child is living for long periods in smaller cities or rural areas and in close contact with the local population.

Infants and children who will live in an area of intermediate or high HBV endemicity for 6 months or more and who are expected to have the preceding exposures should receive the three doses of HBV vaccine. The interval between doses one and two should be 1–2 months. Between doses two and three, the interval should be a minimum of 2 months; the interval between doses one and three should be at least 4 months. The third dose should not be given before the infant is 6 months of age.

Other Vaccines and Immune Globulin

Typhoid Vaccine

Typhoid vaccination is not required for international travel. No data are available concerning the efficacy of typhoid vaccine in infants. Breast-feeding is likely to be protective against typhoid; careful preparation of formula and food from safe water and foodstuffs should protect infants who are not breast-fed. Typhoid vaccine is recommended for children 2 or more years of age traveling to areas where there is a recognized risk of exposure to Salmonella Typhi, particularly if they are traveling to highly disease-endemic areas.

Yellow Fever Vaccine

Because infants are at high risk for developing encephalitis from yellow fever vaccine, vaccination of infants should be considered on an individual basis. Although the incidence of these adverse events has not been clearly defined, 14 of 18 reported cases of postvaccination encephalitis were in infants <4 months old. One fatal case confirmed by viral isolation was in a 3-year-old child. The ACIP recommends that yellow fever vaccine never be given to infants <6 months of age. Yellow fever vaccine can be given to infants and children >9 months of age if they are traveling to or living in areas of South America and Africa where yellow fever infection is officially reported (see Summary of Health Information for International Travel, also known as the “Blue Sheet”) or to countries that require yellow fever immunization (see Chapter 2: Yellow Fever Vaccine Requirements and Information on Malaria Risk and Prophylaxis, by Country). Infants and children >9 months of age should be immunized if they travel to countries within the yellow fever endemic zone (see Chapter 2, Yellow Fever Vaccine Requirements and Information on Malaria Risk and Prophylaxis, by Country, and Maps 3–9 and 3–10). Travelers with infants <9 months of age should be strongly advised against traveling to areas with epidemic yellow fever. Infants 6–8 months of age should be vaccinated only if they must travel to areas of ongoing epidemic yellow fever and a high level of protection against mosquito bites is not possible. Physicians considering vaccinating infants aged <9 months should contact the Division of Vector-Borne Infectious Diseases (970-221-6400) or the Division of Global Migration and Quarantine (404-498-1600) at CDC for advice.

Hepatitis A Vaccine or Immune Globulin for Hepatitis A

Infants and children traveling to low income countries are at increased risk for acquiring hepatitis A virus (HAV) infection, especially if their travel is outside usual tourist routes, if they will be eating food or drinking water in settings of questionable sanitation, or if they will be in contact with local residents in settings of poor sanitation. Although HAV is often not severe in infants and children <5 years of age, those infected efficiently transmit infection to other infants and children and to adults. IG should be given to infants <2 years of age in the same schedule as that recommended for adults (Table 3–7). Children 2 or more years of age should receive the pediatric formulation of HAV vaccine or IG. The first dose of vaccine should be administered as soon as travel to countries with high or intermediate endemicity is considered. Many children will have responded to the vaccine by 2 weeks after the first vaccine dose. One month after receiving the first dose of hepatitis A vaccine, 94%–100% of adults and children will have protective concentrations of antibody. However, travelers who need optimal protection earlier than 4 weeks after the first dose of vaccine should also receive IG at a different injection site.

Meningococcal vaccine

Meningitis primarily affects children and adolescents, with high morbidity and mortality rates. Vaccination is recommended for travel to a disease-endemic area during the dry seasons. The currently available vaccine in the United States is a tetravalent polysaccharide vaccine (unconjugated.) A conjugated vaccine is in large-scale trials and appears to provide good efficacy in children <2 years of age. With the current vaccine, children <2 years old may be able to generate a partial response to serotype A; thus, vaccinating infants going to high-risk areas can provide some degree of protection.

Japanese encephalitis vaccine

JE is transmitted by primarily night-biting Culex mosquitoes in rural areas of Asia and the Pacific Rim. Most reported cases are in children. Although asymptomatic or very minor infections exist in disease-endemic areas, symptomatic infections have up to 25% mortality and 30%-80% incidence of neurologic deficits in survivors. The risk to short-term travelers and those who confine their travel to urban centers is very low. Expatriates and travelers living for prolonged periods in rural areas where JE is endemic or epidemic are at greatest risk. Travelers with extensive unprotected outdoor, evening, and nighttime exposure in rural areas, such as might be experienced while bicycling, camping, or engaging in certain occupational activities, might be at high risk even if their trip is brief.

Influenza vaccine

Influenza vaccine can be used to reduce risk of influenza infection in transmission season (November–February in the Northern Hemisphere, April–September in the Southern Hemisphere, throughout the year in the tropics). Children at high risk for complicated influenza infections should be vaccinated, including those with asthma, cystic fibrosis, and other pulmonary diseases; hemodynamically significant cardiac disease; immunosuppressive disorders or therapy; sickle-cell anemia and other hemoglobinopathies; diseases requiring long-term aspirin therapy; and chronic renal or endocrine diseases.

— Tamara Fisk