The 1999 Harmonized Immunization Schedule

RICHARD KENT ZIMMERMAN, M.D., M.P.H., AAFP Commission on Clinical Policies and Research and AAFP Liaison with the Advisory Committee on Immunization Practices

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 table below). Several important changes occurred this year, and the AAFP had active input into the schedule.

This schedule has been approved by the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics and the American Academy of Family Physicians (AAFP). It indicates the recommended ages for routine administration of currently licensed childhood vaccines. Combination vaccines may be used whenever any components of the combination are indicated and its other components are not contraindicated. Providers should consult the manufacturers' package inserts for detailed recommendations. *--Vaccines are listed under routinely recommended ages. Clear bars indicate range of recommended ages for immunization. Any dose not given at the recommended age should be given as a "catch-up" immunization at any subsequent visit when indicated and feasible. Shaded ovals indicate vaccines to be given if previously recommended doses were missed or given earlier than the recommended minimum age. †--Infants born to hepatitis B surface antigen (HBsAg)-negative mothers should receive the second dose of hepatitis B vaccine at least one month after the first dose. The third dose should be administered at least four months after the first dose and at least two months after the second dose, but not before six months of age for infants. Infants born to HBsAg-positive mothers should receive hepatitis B vaccine and 0.5 mL hepatitis B immune globulin (HBIG) within 12 hours of birth at separate sites. The second dose is recommended at one to two months of age and the third dose at six months of age. Infants born to mothers whose HBsAg status is unknown should receive hepatitis B vaccine within 12 hours of birth. Maternal blood should be drawn at the time of delivery to determine the mother's HBsAg status; if the HBsAg test is positive, the infant should receive HBIG as soon as possible (no later than one week of age). All children and adolescents (through 18 years of age) who have not been immunized against hepatitis B may begin the series during any visit. Special efforts should be made to immunize children who were born in or whose parents were born in areas of the world with moderate or high endemicity of hepatitis B virus infection. ‡--Diphtheria and tetanus toxoids and acellular pertussis vaccine (DTaP) is the preferred vaccine for all doses in the immunization series, including completion of the series in children who have received one or more doses of whole-cell diphtheria, tetanus, pertussis (DTP) vaccine. Whole-cell DTP is an acceptable alternative to DTaP. The fourth dose (DTP or DTaP) may be administered as early as 12 months of age, provided six months has elapsed since the third dose and if the child is unlikely to return at age 15 to 18 months. Tetanus and diphtheria toxoids (Td) is recommended at 11 to 12 years of age if at least five years has elapsed since the last dose of DTP, DTaP or DT. Subsequent routine Td boosters are recommended every 10 years. §--Three Hib conjugate vaccines are licensed for infant use. If PRP-OMP (PedvaxHIB and COMVAX) is administered at two and four months of age, a dose at six months is not required. Because clinical studies in infants have demonstrated that using some combination products may induce a lower immune response to the Hib vaccine component, DTaP/Hib combination products should not be used for primary immunization in infants at two, four or six months of age, unless it is approved by the U.S. Food and Drug Administration for these ages. ||--Two poliovirus vaccines currently are licensed in the United States: inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine (OPV). The ACIP, AAP and the AAFP now recommend that the first two doses of poliovurus vaccine should be IPV. The ACIP continues to recommend a sequential schedule of two doses of IPV administered at ages two and four months, followed by two doses of OPV at 12 to 18 months and four to six years. Use of IPV for all doses also is acceptable and is recommended for immunocompromised persons and their household contacts. OPV is no longer recommended for the first two doses of the schedule and is acceptable only for special circumstances such as: children of parents who do not accept the recommended number of injections, late initiation of immunization which would require an unacceptable number of injections, and imminent travel to polio-endemic areas. OPV remains the vaccine of choice for mass immunization campaigns to control outbreaks due to wild poliovirus. ¶--Rotavirus vaccine is shaded and italicized to indicate: (1) health care providers may require time and resources to incorporate this new vaccine into practice; and (2) the AAFP feels that the decision to use rotavirus vaccine should be made by the parent or guardian in consultation with their physician or other health care provider. The first dose of Rv vaccine should not be administered before six weeks of age, and the minimum interval between doses is three weeks. The Rv vaccine series should not be initiated at seven months of age or older, and all doses should be completed by the first birthday. #--The second dose of MMR vaccine is recommended routinely at four to six years of age but may be administered during any visit, provided at least four weeks has elapsed since receipt of the first dose and that both doses are administered beginning at or after 12 months of age. Those who have not previously received the second dose should complete the schedule by the 11- to 12-year-old visit. **--Var is recommended at any visit on or after the first birthday for susceptible children, i.e., those who lack a reliable history of chickenpox (as judged by a health care provider) and who have not been immunized. Susceptible persons 13 years of age or older should receive two doses, given at least four weeks apart. This schedule is provided by the American Academy of Family Physicians only as an assistance for physicians making clinical decisions regarding the care of their patients. As such, they cannot substitute for the individual judgment brought to each clinical situation by the patient's family physician. As with all clinical reference resources, they reflect the best understanding of the science of medicine at the time of publication, but they should be used with the clear understanding that continued research may result in new knowledge and recommendations.

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/nip 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 http://www.aafp.org, http://www.cdc.org, http://www.atpm.org/ 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

REFERENCES

1. Reis EC, Holubkov R. Vapocoolant spray is equally effective as emla cream in reducing immunization pain in school-aged children. Pediatrics 1997;100:1-6.
2. Zimmerman RK, Spann SJ. Poliovirus vaccine options. Am Fam Physician 1999;59:113-26.
3. Tucker AW, Bresee JS, Haddix AC, et al. Cost-effectiveness analysis of a rotavirus vaccine program in the U.S. JAMA 1998;279: 1371-6.
4. Rennels MB, Glass RI, Dennehy PH, et al: Safety and efficacy of high-dose rhesus-human reassortant rotavirus vaccines--report of the national multicenter trial. Pediatrics 1996;97:7-13.
5. Zimmerman RK, Barker WH, Strikas RA, et al. Developing curricula to promote preventive medicine skills: The Teaching Immunization for Medical Education (TIME) Project. JAMA 1997;278:705-11.

Dr. Zimmerman is an associate professor in the Department of Family Medicine and Clinical Epidemiology at the University of Pittsburgh (Pa.) School of Medicine, with a secondary appointment in the Department of Health Services Administration.

Copyright © 1999 by the American Academy of Family Physicians.
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