PHYSICIANS are being advised that infants and children immunized with the Haemophilus influenzae type b conjugate vaccine PedvaxHIB© (Meningococcal Protein Conjugate) between December 1990—when the vaccine was licensed—and March 1992 should be given an additional dose.
The first 16 lots of PedvaxHIB distributed to physicians may have lower than expected immunogenicity, the manufacturer says.
Lots producing lower than expected immunogenicity are characterized by certain biochemical markers, and all of them have been identified, says Paul M. Mendelman, MD, clinical research director, Merck Sharp & Dohme research laboratories, West Point, Pa.
The issue now is those who have received vaccine from these lots, says Merck's Wayne Morges, PhD. It is impossible to define the future risk to any of these children, he says, so "our recommendation is that those who received vaccine from these lots should be given one additional dose in order to be assured of continuing protection."