Pediatric Immunization Update: Why More Shots?

By Leonard Friedland, MD


When taking a pediatric medical history, we have all been taught to ask, "Are your child's immunizations up to date?" Prior to the late 1980s, the recommended childhood vaccination series was straightforward and easy to commit to memory. This is not the case in 1997, as the last decade has brought the following changes and additions:

    · the addition of a second dose of measles-mumps-rubella vaccine;

    · routine immunization against Haemophilus influenzae type B;

    · the introduction of varicella zoster virus vaccine immunization for susceptible persons;

    · routine immunization against hepatitis B;

    · the recent FDA approval of acellular pertussis vaccines for use in infancy;

    · the recommended use of a sequential inactivated polio vaccine-oral polio vaccine schedule for routine immunization against poliomyelitis.

Shown in the table is the "Recommended Childhood Immunization Schedule-United States, January-December 1997."1 The information presented is approved by three important organizations: the Advisory Committee on Immunization Practices (ACIP), the American Academy of Pediatrics, and the American Academy of Family Physicians. Assuming that it may be difficult for you to keep up with all of these changes (it is for me), I would like to review what a recent medical journal editorial referred to as "the ever-changing world of pediatric vaccines: why are we giving more shots?"2 My comments will focus on the eight superscripts in the table.

aVaccines: The schedule refers to FDA-licensed vaccines and the recommended age for routine administration. Because additions to the vaccination schedule bring another injection, some "well-baby visits" may result in four injections (ouch!). Researchers are actively investigating whether vaccines can be combined in the same syringe and still induce good immunity. Some combination vaccines are available, and these may be used when administration of all the components of the combination vaccine is indicated. Combination vaccines licensed for use in the United States include DTP+HiB, DTaP+HiB, and hepB+HiB. The child's age at which these combination vaccines can be effectively given varies, and health care providers should refer to the combination vaccine's package insert for details.

bHepatitis B: Universal hepatitis B (hepB) vaccination of infants was recommended in 1991. The routine hepB vaccination series should begin at birth, with the second dose given at 2 months for infants whose mothers are hepatitis B surface antigen negative. Acceptable ranges are from birth through 2 months for the first dose and from 1 through 4 months for the second dose, provided that at least one month elapses between these doses. The third dose should be administered at 6 through 18 months.

cHepatitis B: Since universal hepB vaccination of infants was not recommended prior to 1991, there are many children and adolescents who have not been vaccinated against hepB in infancy-catch-up vaccination with the three-dose series may begin at any childhood visit. Routine vaccination of adolescents 11 to 12 years old who have not been previously vaccinated is an effective strategy for lowering the incidence of hepB infection and assisting in the elimination of hepB transmission.

dDiphtheria, Tetanus, and Pertussis (DTP): Whole-cell DTP vaccines, although safe, are associated with common adverse events such as local erythema, swelling, and tenderness, along with fever, irritability, and drowsiness. Infrequently, febrile seizures, inconsolable crying, and hypotonic-hyporesponsive episodes can occur. The adverse events appear to be mostly related to the pertussis antigens in the whole cell vaccine. Concerns about safety have led researchers to develop "safer" pertussis vaccines that continue to have high efficacy. These less reactogenic vaccines are referred to as "acellular" pertussis vaccines. DTaP (diphtheria, tetanus toxoid, and acellular pertussis vaccine) is now the preferred vaccine for all doses in the vaccination series, including children who have received greater than one dose of whole-cell DTP.

eH. influenzae type B (HiB): In 1985, the first HiB vaccines were licensed for use in the United States. Physicians have all witnessed the fantastic decline in the incidence of HiB disease since the mid-1980s. Three HiB conjugate vaccines are licensed for infant use in the United States. If PedvaxHiB (from Merck) is used at 2 and 4 months, then a dose at 6 months is not required. Any of the three HiB vaccines can be used at the time of the 12-15-month booster.

fPolio: As of early 1997, the recommendations for polio immunization in the United States had been revised by ACIP. The recommended schedule has changed from four doses of oral poliovirus vaccines (OPV) to a sequential schedule of two doses of inactivated poliovirus vaccines (IPV) followed by two doses of OPV. The recommendations have been changed for three reasons: 1) paralytic poliomyelitis attributable to indigenously acquired wild poliovirus has not occurred in the United States since 1979; 2) the risk for importation of wild poliovirus into the United States is very small; and 3) vaccine-associated paralytic poliomyelitis continues to occur in the United States (eight to 10 cases annually in the past 15 years). ACIP recommends this immunization schedule: IPV at 2 and 4 months; OPV at 12-18 months and 4-6 years. IPV continues to be the only poliovirus vaccine recommended for immunocompromised persons and their household contacts.

gMeasles-Mumps-Rubella (MMR): The late 1980s and early 1990s witnessed a dramatic increase in measles cases in the United States In 1989, ACIP and AAP recommended that all children receive a second dose of measles-containing vaccines. The second dose of MMR is routinely given at either 4-6 or 11-12 years.

hVaricella: Varicella virus vaccine was licensed by the FDA in March 1995 for use in healthy persons older than 12 months. It is recommended that all children receive varicella virus vaccine between 12 and 18 months. Varicella vaccine is recommended for all children and adolescents older than 19 months who have not previously received the vaccine and who lack a reliable history of chickenpox. Many practitioners will administer the varicella virus vaccine to susceptible adolescents during the so-called "routine immunization visit" at 11-12 years.

References

    1. Committee on Infectious Diseases. Pediatrics 1997; 99:136-138.

    2. Schleiss MR. J Pediatr 1997;130:505.

Dr. Friedland is Assistant Professor of Pediatrics and Medicine, Temple University School of Medicine, Director of Pediatric Emergency Medicine, Temple University Hospital, Philadelphia, PA.