Concerns Arise about Some Vaccines
Fall 1999

Rotavirus vaccine put on hold

This action was taken when preliminary data appeared to link the rotavirus vaccine with intussusception, a condition in which the intestine telescopes upon itself. Between August 1998, when the vaccine was approved, and July 7, 1999, 13 cases of intussusception occurred in infants within a week of vaccination. Since July, additional cases have been identified.

Although no conclusive evidence links the rotavirus vaccine to intussusception, the CDC recommends that:

• Clinicians should postpone giving rotavirus vaccine to children pending  results of CDC case-control studies, probably in November.
• If a child develops any of the symptoms of intussusception (vomiting, black stools, severe pain, abdominal bleeding) within three weeks of vaccination, immediate medical care should be sought.
• All cases of intussusception which occur following administration of rotavirus vaccine should be reported to the Vaccine Adverse Event Reporting System (VAERS), at 800-822-7967.

Mercury in vaccines

The American Academy of Pediatricians and the US Public Health Service also issued a joint statement in July regarding thimerosal, a mercury-containing preservative found in some vaccines (see chart below). Infants who receive thimerosal-containing vaccines at several visits may be exposed to more mercury, a known neurotoxin, than is recommended by federal guidelines. This is of particular concern in very small, premature infants.

Mercury exposure and hepB vaccination

Adjusting the timing of hepatitis B vaccinations within the ranges given in the AAP immunization schedule (see Summer ‘99 EPSDT Care for Kids Newsletter) can minimize thimerosal exposure for very young infants. The immunization schedule for Infants born to HBsAG-positive women and women who were not tested for HBsAG during pregnancy remains the same.

Infants born to HBsAG-negative women may receive COMVAX, a thimerosal-free hepB vaccine, beginning at the 2-month visit. (COMVAX, a combination hepB/Hib vaccine, is not approved for use before 6 weeks of age due to decreased response to the Hib component). If COMVAX is not available, hepB vaccination should begin at 6 months. Either of these approaches allows for the completion of the series by 18 months of age.

Small, premature infants should not be vaccinated for hepB until the infant reaches a size and developmental level that corresponds to that of a term infant.

Work is underway to produce thimerosal-free vaccines. In the meantime, the AAP and the Public Health Service continue to recommend that children be immunized against the diseases listed in the 1999 Recommended Childhood Immunization Schedule. Health care providers are advised to discuss all vaccines with parents, and to point out that the risks resulting from not vaccinating children still outweigh those posed by thimerosal-containing vaccines.

Visit the American Academy of Pediatricians web site for more information about:

• Rotavirus vaccine (AAP Policy)
• Thimerosal in vaccines