The collaboration between the American Academy of Family Physicians (AAFP), the American Academy of Pediatrics (AAP), and the Advisory Committee on Immunization Practices (ACIP) continues with the 1998 childhood immunization schedule (see page 157). The changes this year involve expansion of hepatitis B vaccine recommendations for all adolescents, expansion of the timing of the third dose of inactivated poliovirus vaccine (IPV) to as early as six months of age, and uniform recommendations for administration of the second dose of measles, mumps and rubella (MMR) vaccine at four to six years of age.
Hepatitis B Vaccine
The ACIP recently recommended that all children and adolescents 18 years of age and younger who were not previously vaccinated against hepatitis B should be vaccinated with hepatitis B vaccine. The Vaccines for Children Program was expanded, effective March 1998, to cover hepatitis B vaccine through 18 years of age. These expansions simplify current recommendations and should reduce the incidence of hepatitis B in adolescents who engage in behaviors that place them at risk for being infected.
Acellular Pertussis Vaccine
Three acellular pertussis vaccines have been licensed for use in infancy. Acellular pertussis vaccines have 25 to 50 percent fewer instances of the common adverse effects than whole-cell pertussis vaccines and fewer instances of moderate to severe adverse effects. The efficacy of the acellular pertussis vaccines generally is comparable with that of whole-cell pertussis vaccines.1–3 Because of differences in study design, the safety and efficacy rates cannot generally be compared between trials of the various acellular pertussis vaccines. Methodologic differences exist in general design, degree of blinding, case definition, type of confirmation of pertussis disease, study population and vaccine schedule used. Diphtheria and tetanus toxoids and acellular pertussis (DTaP) vaccine and Haemophilus influenzae type b (Hib) vaccine given separately cause less pain than the whole-cell DTP/Hib combination vaccines. My office has stopped using whole-cell pertussis vaccine in favor of acellular pertussis vaccine.
Haemophilus influenzae type b Vaccine
Recent studies4–6 have shown that Hib conjugate vaccines are generally interchangeable. If PRP-OMP (PedvaxHIB) Hib vaccine is administered at two and four months of age, a dose at six months is not required. Tables are available to determine the number of doses needed if a child starts the Hib series late.7
The AAFP continues to recommend that physicians and parents jointly decide among the all oral poliovirus vaccine (OPV) schedule, the all IPV schedule and the sequential IPV/OPV schedule. This choice should take into account the potential benefits, costs and risks of each schedule. The bar on the 1998 childhood immunization schedule for the third dose of poliomyelitis vaccine has been extended down to six months of age, as it appeared in the 1996 schedule. Previously, the third dose of IPV was approved by the U.S. Food and Drug Administration beginning at 12 months of age, but a recent change allowed its use as early as six months of age. Thus, the all IPV and all OPV schedules are the same: two months, four months, six to 18 months, and four to six years. The sequential IPV/OPV schedule involves two doses of IPV (two and four months of age), followed by two doses of OPV (12 to 18 months and four to six years).
The purpose of the sequential schedule is to reduce vaccine-associated paralytic poliomyelitis, while at the same time providing eventual mucosal immunity and limiting the number of injections in the second year of life. Many children with immunodeficiency disease are diagnosed between four and 12 months of age. Thus, it's somewhat safer to delay the third dose of the sequential schedule until 12 months of age, although administration as early as six months of age is allowable. In my practice, parents differ in their choice of poliomyelitis schedules; some prefer the all OPV schedule to avoid injections and because they themselves and their older children received OPV; others prefer to avoid the small risk of vaccine-associated paralytic poliomyelitis and accept the increased number of injections that are necessary with the all IPV or sequential IPV/OPV schedules.
Measles, Mumps and Rubella Vaccine
The second dose of MMR vaccine is now recommended by the AAFP, ACIP and AAP at four to six years of age; administration at this age is feasible as other vaccines are scheduled for this same time period; furthermore, adverse effects appear to occur less often when the second dose of MMR is given at this age, compared with age 11 to 12 years.8 Children seven years of age or older who did not previously receive the second dose of MMR can be caught up on the vaccination at any visit. Age 11 to 12 years is a recommended time to evaluate immunization status and administer any needed vaccines.
Joint Recommendations on Related Topics
In addition to the recommended childhood immunization schedule, the ACIP, AAFP and AAP have developed joint recommendations on immunization of adolescents9 and, to be published soon, joint recommendations on the use of reminder and recall systems to increase vaccination rates.10 Collaboration by these groups results in uniform recommendations and may decrease the confusion that differing policies can create.
Physicians will need to make extra efforts to keep current on vaccinations and incorporate them into their practice. AAFP resources include a statement on the Recommended Childhood Immunization Schedule with additional information on poliomyelitis vaccine options (see page 158), the Age Charts for Periodic Health Examination and the Vital Signs program. The Association of Teachers of Preventive Medicine has up-to-date educational materials for medical students and residents.11 Useful information may be found on Web sites developed by the AAFP and the Centers for Disease Control and Prevention. The AAFP Web site address is https://www.aafp.org. The CDC Web site address is http://www.cdc.gov/epo/MMWR/mmwr.html.
The vaccination schedule, recommendations and products available are changing rapidly. Several vaccines should be licensed in the next year. Rapid progress is being made in rotavirus and pneumococcal conjugate vaccines for children and Lyme disease vaccine for high-risk adults.