190624 Observational Safety Study of Febrile Convulsion Following MMRV Vaccination in a Managed Care Setting

Tuesday, October 28, 2008: 1:05 PM

Steven J. Jacobsen, MD, PhD , Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA
Bradley K. Ackerson, MD , Pediatric Services, Kaiser Permanente Southern California, Harbor City, CA
Lina S. Sy, MPH , Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA
Patricia Saddier, MD, PhD , Epidemiology, Merck Research Laboratories, North Wales, PA
Trung N. Tran, PhD , Epidemiology, Merck Research Laboratories, North Wales, PA
Tonia L. Jones, PhD , Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA
Janis F. Yao, MS , Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA
Fagen Xie, PhD , Research & Evaluation, Kaiser Permanente Southern California, Pasadena, CA
Craig T. Cheetham, PharmD , Pharmacy Analytical Service, Kaiser Permanente Southern California, Downey, CA
A combined measles, mumps, rubella, varicella live vaccine (MMRV, Merck and Co., Inc., US) was recently licensed in the US. Pre-licensure clinical trial data showed a significant increase in fever following MMRV vaccination as compared to the vaccines given separately (MMR+V). This post-licensure retrospective cohort study was undertaken to assess the incidence of febrile convulsion following MMRV.

31,298 children ages 12-60 months who received MMRV in February 2006-June 2007 in a managed care organization were included in the study. Subjects were optimally matched on age, sex, and calendar date of vaccination to children who received MMR+V concomitantly in January 2004-January 2006, before MMRV availability. Potential cases of febrile convulsion were identified through administrative data and adjudicated by expert panel, according to pre-specified criteria.

During the 30 days post–vaccination, there were 128 and 94 potential convulsion cases in the MMRV and MMR+V groups, respectively. After review of available medical charts and adjudication, there were 84 cases of confirmed febrile convulsion, 44 (1.41/1000) and 40 (1.28/1000) in the MMRV and MMR+V cohorts, respectively (RR= 1.10, 95% CI= 0.72, 1.69). In days 5-12 following vaccination, a pre-specified period of interest, the respective numbers were 22 (0.70/1000) and 10 (0.32/1000) (RR=2.2, 95% CI=1.04, 4.65).

These data suggest that the risk of febrile convulsion is not different in children vaccinated with MMRV vs. MMR+V in the month following vaccination but increased in days 5-12 when post-vaccination fever is most likely to occur, underscoring the importance of monitoring children during this critical time period.

Learning Objectives:
To determine if febrile convulsion is more common following vaccination with MMRV vs. MMR+V

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: Epidemiologist
Any relevant financial relationships? Yes

Name of Organization Clinical/Research Area Type of relationship
Merck & Co., Inc. Infectious diseases/Vaccines Consultant and Independent Contractor (contracted research and clinical trials)

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.

See more of: Late Breaker Infectious Disease Epidemiology
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