Routine Immunizations for Pediatric Travelers
Special Update & Report
By Philip R. Fischer, MD, DTM&H, and Robert M. Jacobson, MD
Philip Fischer is Professor of Pediatrics, Division of Pediatric and Adolescent Medicine, Mayo Clinic, Rochester, MN, and Robert M. Jacobson is Professor of Pediatrics, Chair, Department of Pediatric and Adolescent Medicine, Director, Clinical Trials, Mayo Clinic, Rochester, MN
Dr. Fischer reports no financial relationship relevant to this field of study, and Dr. Jacobson does research for Chiron and VaxGen.
Synopsis: The schedule of routine vaccinations for children in the United States is modified regularly. Travel medicine practitioners should be aware of current recommendations so that traveling children can benefit from appropriate pre-travel care both during and after their trips.
Sources: American Academy of Pediatrics Committee on Infectious Diseases. Recommended Childhood and Adolescent Immunization Schedule—United States, 2006. Pediatrics. 2006;117:239-240; CDC. Mumps Epidemic—Iowa, 2006. MMWR Morb Mortal Wkly Rep. 2006;55:366-368.
With such rapid advances in immunization science and with additional vaccines frequently becoming available, expert groups advising the American public about immunization practices standardized their recommendations a decade ago. Annually, updates are published by the American Academy of Pediatrics.
This year, several established and emerging innovations are particularly relevant to the care of traveling children. The newly developed meningococcal vaccine should be given to all 11- to 12-year-olds and to all unimmunized individuals entering high school. Hepatitis A is now recommended for all American 1- to 2-year-olds. Adolescents should now be immunized against pertussis as part of their tetanus booster. All children aged 6 to 59 months should receive influenza vaccine.
A recent mumps outbreak has affected hundreds of people in the Midwestern United States. Of 219 Iowa patients evaluated by the CDC, the median patient age was 21 years. At least two-thirds of them had received 2 vaccine doses. With new combination formulations becoming available, mumps vaccination is now urged for unprotected individuals.
New Recommendations
Meningococcus: Meningococcal disease is well-known and respected by travel medicine practitioners. Even in the United States, however, there are approximately 2000 cases of meningococcal disease each year. Despite antibiotic therapy being available, about 10% of affected individuals die of their disease. The new quadrivalent (still just for strains A, C, Y, and W135) is at least as immunogenic to the older vaccine preparations (98-100%), but has a longer duration of protection (8 vs 3-5 years). Despite initial concerns, the risk of Guillain-Barré syndrome does not appear to be increased following use of this vaccine. The new vaccine is preferred for individuals 11-55 years of age. Vaccination is recommended routinely for 11- to 12-year-olds and for older adolescents who did not receive the older (polysaccharide) vaccine during the preceding 5 years.
Hepatitis A: In the late 1990s, 11 US states accounted for 70% of all US cases of hepatitis A. Children were frequently identified as the source of infection that spread to adults. Since 1999, focused vaccination of 2-year-olds in those 11 states has been recommended. As a result, some areas have reported a 90% decrease in cases of adult hepatitis A, and two-thirds of US cases now occur among the remaining unvaccinated persons in 39 states. Between 12 and 24 months of age, 96% of vaccine recipients convert to seropositivity after the first dose of vaccine, and all recipients are found to be seropositive following their second dose, 6 or more months later. The 2 major hepatitis A vaccines, recommended for younger infants in other countries for years, are now licensed for use in 1-year-olds in the United States. It is now recommended that all 1-year-olds be vaccinated against hepatitis A, and that vaccination be considered for older children who were not previously vaccinated. Of course, all children traveling to endemic countries would be candidates for vaccination.
Pertussis: Pertussis vaccination for health care workers was reviewed in last month's Travel Medicine Advisor. While infection is most severe, and even potentially fatal during infancy, adolescents and adults in whom vaccine-induced immunity has generally waned, serve as the common source of infection for infants. New combination vaccines include reduced antigen loads, and are both effective and tolerably safe. These new Tdap vaccines are recommended for adolescents who have not yet received their tetanus-diphtheria booster, and the Tdap vaccine is encouraged for adolescents and adults who are in contact with young children and who received the Td booster at least 2-5 years earlier.
Influenza: Vaccination against influenza has been recommended for high-risk individuals. Previously, routine vaccination of children was focused on reducing influenza-related hospitalizations and deaths by targeting children 6-23 months of age. Now, to reduce episodes of illness and outpatient visits as well, vaccination is recommended for all children aged 6-59 months and for those older children and adults who live with or care for pre-school-aged children.
Rotavirus: Worldwide, rotavirus diarrhea kills half a million children each year. In the United States, 2,700,000 children are infected by rotavirus each year, with a cost to the American public of nearly $1 billion. The previously licensed rotavirus vaccine was removed from the market when post-licensure surveillance identified an increased risk of intussusception. Now, a new vaccine has been licensed. The new vaccine is not rhesus-derived and shows less intestinal virus replication. In over 70,000 studied children, no increased risk of intussusception was identified. Nonetheless, there is concern that late administration of older children could pose a risk of intussusception. The new recommendation is that all infants receive rotavirus vaccine at 2, 4, and 6 months of age, with the first dose given no later than 12 weeks of age and the final dose no later than 32 weeks of age. Travel medicine practitioners should ensure that traveling infants in this age group have been vaccinated, but they should not risk use of the vaccine beyond these ages.
Live Vaccines in Infants
The recent fading outbreak of mumps in the midwestern United States has heightened awareness of the importance of obtaining adequate protection using current live virus vaccines. A single dose of the combination measles-mumps-rubella vaccine given at 1 year of age (when competing maternally-derived antibody titers would have waned) is 80-90% protective against these 3 infections. A second dose is routinely given after infancy, but prior to school entry, and results in 90-95% protection against the 3 infections. As illustrated in the Iowa outbreak, however, compliance with recommended vaccine programs does not insure complete protection. During an active outbreak of measles, mumps, or rubella, or when a child will be traveling, the second dose may be given as early as 4 weeks after the first dose. In an effort to reduce the number of injections a young child receives, a new combination vaccine that also includes varicella vaccine is now recommended for routine use as the first dose in children aged 12 months to 12 years.
What should be done for infants traveling to areas endemic for yellow fever? Fourteen of the 18 cases of vaccine-associated neurotrophic disease have been in infants less than 4 months of age.2 To decrease the risk of this severe reaction, yellow fever vaccine is considered contraindicated for children less than 6 months of age. Use of yellow fever vaccine in children 6-9 months of age should be undertaken very cautiously, if at all, usually in consultation with experts such as those at the CDC (404-498-1600). For infants who must spend time in areas where yellow fever is a risk, insect avoidance measures (clothes, impregnated bed nets, DEET) are vitally important.
Accelerated Vaccination Schedules
The routine schedules for vaccination of American children are intended for children in routine situations. While foreign travel is increasingly common, it is not yet a routine part of infancy. Thus, routine schedules can be adapted to meet the needs of traveling children. In addition to adding travel-associated vaccines, routine vaccine schedules can be accelerated to provide earlier protection for children at increased risk due to potential travel-related exposures.
Hepatitis B vaccine may be given at birth, with the second dose at 1 month of age. The final dose, ensuring maximal protection, could be given at 6 months of age. Diphtheria, tetanus, pertussis, Haemophilus influenza type b, and inactivated polio vaccines are safe and effective when given as early as 6 weeks of age, with subsequent doses as early as 6 week intervals. Pneumococcal vaccine is likely effective at this accelerated rate as well, but data are not available to fully document this currently.
Maternally-derived measles antibody titers subside between 6 and 12 months of age. Thus, children traveling to areas where measles, mumps, and/or rubella are common can receive the combined vaccine as early as 6 months of age—with the thought that it would provide protection for those in whom maternal antibodies are no longer protective. Since the vaccine at this time might not remain fully protective, subsequent doses following the routine schedule should also be given. Similarly, hepatitis A vaccine, though not licensed for use prior to 1 year of age, could provide protection in younger infants who do not have maternally-derived antibody. Varicella vaccine has not been tested prior to 12 months of age, so is not routinely recommended in younger infants.
The older polysaccharide meningococcal vaccine is not completely effective during infancy. It may be used as early as 3 months of age if partial protection is desired. For continued protection, a repeat dose would need to be given sooner (after 2-3 years) than in children vaccinated initially after their fourth birthday (after 3-5 years). Pre-travel consultations provide an excellent opportunity to help pediatric travelers catch up with new recommendations for routine vaccination. Careful attention to the age and timing of vaccination can also help ensure that each traveling child is maximally protected against many of the infectious risks they may encounter.
References
- www.cdc.gov/nip/news/pr/pr_rotavirus_feb2006.pdf, Accessed May 5, 2006.
- www2.ncid.cdc.gov/travel/yb/utils/ybGet.asp?section=children&obj=child-vax.htm. Accessed May 5, 2006.
You have reached your article limit for the month. Subscribe now to access this article plus other member-only content. TESTING
- Award-winning Medical Content
- Latest Advances & Development in Medicine
- Unbiased Content