Review of the Safety of the Measles-Mumps-Rubella-Varicella (MMRV) vaccine. Preliminary findings from the Vaccine Adverse Events Reporting System

Learning Objectives for this Presentation:
By the end of the presentation participants will understand the safety evidence for MMRV in children aged 12-23 months.

Background:
In 9/2005, MMRV (Proquad®) was licensed in the U.S. The clinical trials identified a safety signal for fever and measles-like rash for days 5-12 post-vaccination. After licensure, the Centers for Disease Control and Prevention (CDC) and the Food and Drug Administration (FDA) implemented passive surveillance and observational safety studies.

Objectives:
To investigate MMRV adverse events reported to the Vaccine Adverse Event Reporting System (VAERS) during the first two years post-licensure.

Methods:
We reviewed MMRV AE reports for children aged between 12-23 months, administered during 2005 to 2007. We used MedDRA codes to identify adverse event reports, and data mining to identify safety concerns. We confirmed the AE diagnosis using medical record reviews and standardized case definitions.

Results:
As of September 30, 2007, VAERS received a total of 1703 MMRV adverse event (AE) reports, 712 of which were for children ages 12-23 months. Of them, a total of 71 (10%) were classified as serious.
The most common serious AEs reported for children ages 12-23 months were fever, febrile seizures, other seizures, vomiting and rash.
Among seizures, a total of 5 seizure cases with onset between 5-12 days post-vaccination were identified after MMRV-only use among children ages 12-23 months. All 5 cases were febrile seizures and occurred 7-10 days post-vaccination.

Conclusions:
Findings from passive surveillance are compatible with those from pre-licensure clinical trials. Ongoing analysis of passive surveillance data and results from observational studies will help further describe the vaccine's safety profile.