MMRV vaccine and febrile seizures

On February 27, 2008, information was presented to the Advisory Committee on Immunization Practices (ACIP) on the risk of febrile seizures after combination measles, mumps, rubella, and varicella (MMRV vaccine: ProQuad®) vaccination in children aged 12–23 months. ACIP voted to state no preference for use of combination MMRV vaccine over separate administration of MMR and varicella vaccines. Physicians may administer MMRV vaccine or MMR and varicella vaccines separately, according the routine immunization schedule. On February 27, 2008, the Food and Drug Administration approved a revised label for MMRV vaccine to include new and evolving information on the risk of febrile seizures after MMRV vaccination. MMRV vaccine is currently in very limited distribution in the United States; however, some clinics may have MMRV vaccine in stock.

Preliminary results from a Centers for Disease Control and Prevention (CDC) postlicensure MMRV safety study found that the rate of febrile seizures during the 7–10 days after vaccination was about 2 times higher in children who received MMRV vaccine (9 per 10,000 children vaccinated), compared with children who received MMR and varicella vaccines separately at the same visit (4 per 10,000 children vaccinated). The interim analysis of Merck’s postmarketing study showed that during the 5–12 days after vaccination, the rate of febrile seizures was about 2.5 higher in the children who received MMRV vaccine (5 per 10,000 children vaccinated), compared with children who received with MMR and varicella vaccines separately at the same visit (2 per 10,000 children vaccinated).