The collaboration between the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics (AAP) and the American Academy of Family Physicians (AAFP) continues with the 1999 harmonized childhood immunization schedule (see page 204). Several important changes occurred this year, and the AAFP had active input into the schedule.
In the schedule, DTaP (diphtheria and tetanus toxoids and acellular pertussis) now appears where DTaP or DTP (diphtheria and tetanus toxoids and pertussis) previously appeared. DTaP has about one fourth to one half of the adverse effects of whole cell DTP and, therefore, is preferred. Whole-cell DTP is still acceptable; however, the pain that a child endures from separate injections of DTaP and Haemophilus influenzae type b (Hib) vaccines is less than the pain caused by injection of combination DTP-Hib vaccines. Ways to reduce pain at the injection site include use of vapocoolant sprays just before injection1 and use of the combination hepatitis B and Hib vaccine.
Some studies of the combined acellular DTaP and Hib vaccine found lower antibody titers from the Hib vaccine when the combination was given during the first 12 months of life. Thus, combination DTaP-Hib vaccines should not be used in the first 12 months of life unless the U.S. Food and Drug Administration approves use during infancy.
The second change in the 1999 schedule involves poliovirus vaccines. Vaccine-associated paralytic poliomyelitis is a disabling illness that on rare occasions occurs after oral poliovirus vaccine (OPV) administration but not after inactivated poliovirus vaccine (IPV) administration. The risk of this condition is one case per 750,000 doses distributed for the first dose of OPV and one case per 2.4 million doses of OPV distributed overall. Because of the risk of vaccine-associated paralytic poliomyelitis, most parents prefer a vaccine schedule that starts with IPV even though extra injections are required. New studies show that high immunization rates can be achieved with an IPV starting schedule in disadvantaged populations.
Because indigenous wild poliovirus has been eliminated from this hemisphere, because IPV is safer than OPV and because high immunization rates can be achieved with IPV, the AAFP has changed its policy. The AAFP now recommends that the first two doses of poliovirus vaccine be IPV—that is, either an all IPV schedule or a sequential schedule of two doses of IPV followed by two doses of OPV. OPV is no longer recommended for the first two doses and is acceptable only under special circumstances, such as in the case of parents who do not accept the recommended number of injections. An article further describing the rationale for starting with IPV appears in this issue of American Family Physician. 2
The third change in the 1999 schedule is the addition of rotavirus vaccine. Rotavirus is the most common cause of severe gastroenteritis in preschool-age children in the United States, resulting in about 50,000 hospitalizations each year. Rotavirus also causes about 160,000 emergency department visits and about 410,000 physician visits each year.3 Rotavirus is highly contagious and is transmitted primarily by the fecal-oral route. A live tetravalent rhesus rotavirus vaccine (RRV) was licensed in 1998, based on a modified Jennerian (i.e., smallpox-like) approach to vaccination. The vaccine is moderately effective against diarrhea and very effective against dehydration and severe diarrhea.
In a double-blind, placebo-controlled trial conducted in the United States,4 the efficacy of RRV over one season was found to be 49 percent for gastroenteritis (95 percent confidence interval of 31 to 63 percent), 73 percent for gastroenteritis resulting in physician intervention (95 percent confidence interval of 54 to 84 percent), 80 percent for very severe rotavirus gastroenteritis (95 percent confidence interval of 56 to 91 percent), and 100 percent against dehydration. Although most children do not have reactions to RRV, low-grade fever, diarrhea and irritability occur in some children. Cost-effectiveness analyses suggest that RRV will be cost-saving to society.3 RRV is administered orally.
The shading in the schedule for rotavirus vaccine is intended to convey two things. First, time and resources will be needed for many physicians to incorporate this vaccine into their practice; in particular, insurance companies will need to cover the vaccine and increase capitation rates appropriately, and a federal contract will need to be negotiated for coverage through the Vaccines for Children program. Second, the AAFP feels that the decision to use rotavirus vaccine should be made by the parent or guardian in consultation with the physician.
Federal law requires physicians to provide federal Vaccine Information Statements to parents before vaccination for almost all childhood vaccines; the vaccine statements may be downloaded from the Centers for Disease Control and Prevention Web site at http://www.cdc.gov/ or obtained from health departments.
Progress in developing new vaccines continues at an amazing rate; physicians will need diligence to keep current. Several Web sites that may be helpful are https://www.aafp.org, http://www.cdc.org, http://www.atpm.org/cme/cme.htm and http://www.immunize.org. Resources for medical educators include the Group on Immunization Education of the Society of Teachers of Family Medicine and the Teaching Immunization for Medical Education (TIME) project.5