Combined measles-mumps-rubella-varicella vaccine and febrile convulsions: the risk considered in the broad context.

INTRODUCTION Studies on quadrivalent measles, mumps, rubella, and varicella (MMRV) vaccines have indicated a 2-fold increased relative risk of febrile convulsion (FC) after the first dose compared to MMR and V administered at the same medical visit (MMR+V). AREAS COVERED This narrative review contextualizes FC occurrence after the first MMRV vaccine dose from a clinical perspective and outlines approaches to attenuate FC occurrence post-vaccination. EXPERT OPINION While the relative FC risk increases after the first dose of MMRV compared to MMR+V vaccine in measles-naïve infants, the attributable risk is low versus the overall FC risk in the pediatric population triggered by other causes, like natural exposure to pathogens or routine vaccination. No increased risk of FC has been reported after MMRV co-administration with other routine vaccines compared to MMRV alone. Based on our findings and considering the MMRV vaccination benefits (fewer injections, higher coverage, better vaccination compliance), the overall benefit-risk profile of MMRV vaccine is considered to remain positive. Potential occurrence of FC in predisposed children (e.g. with personal/family history of FC) may be attenuated if they receive MMR+V instead of MMRV as first dose. It is also important to monitor vaccinees for fever during the first 2 weeks post-vaccination.