Measles Vaccines Not Associated With Febrile Seizure Risk

Lara C. Pullen, PhD

April 02, 2012

April 2, 2012 — The combination vaccine for measles-mumps-rubella-varicella (MMRV) carries the same low febrile seizure risk as the measles-mumps-rubella plus varicella (MMR + V) vaccines in children aged 4 to 6 years old. This risk is 1 or fewer febrile seizure per 15,570 MMRV doses and 1 or fewer febrile seizure per 18,282 MMR + V doses.

Nicola P. Klein, MD, PhD, from Kaiser Permanente Vaccine Study Center in Oakland, California, and colleagues presented the results of their medical record reviews in an article published online April 2 in Pediatrics. The authors used data from the Vaccine Safety Datalink and examined risk for febrile seizures after measles-containing vaccines. They concluded that MMRV and MMR + V are not associated with an increased risk for febrile seizures among 4- to 6-year-olds.

Mark H. Sawyer, MD, from the University of California, San Diego, commented on the article for Medscape Medical News. He explained by email that the bottom line for physicians is that: "There is no concern for giving either MMRV or MMR + varicella vaccine to [4- to 6-year-old] children. Many physicians may prefer to give MMRV because it is 1 less injection. Now they can do that without any concern about risk of febrile seizures. This gives both physicians and parents a choice to use whichever vaccines they prefer."

The study reviewed data from 86,750 doses of MMRV that were administered to 4- to 6-year-old children from January 2006 through October 2008. The authors noted seizure risk for 6 weeks post–vaccine administration. The same was done for 67,438 children who received MMR + V.

Seizures were identified by International Classification of Diseases, Ninth Revision, codes in the electronic data. Outpatient fever visits were also noted.

Only a few studies have examined the risk for febrile seizures after MMR alone in 4- to 6-year-olds. In general, fever visits after all measles-containing vaccines are quite low for children aged 4 to 6 years.

This study documented similar results, with only rare seizures throughout days 0 to 42 and no peak in seizures from days 7 to 10. Although there were 4 post-MMRV seizures during days 7 to 10, 2 of the patients had afebrile seizures, and 1 record was excluded, as neither a fever nor a seizure were documented.

The authors therefore documented 1 febrile seizure 7 to 10 days after MMRV and 0 febrile seizures after MMR + V. The authors calculated this as a febrile seizure risk of 1 per 86,750 MMRV doses (95% confidence interval, 1 per 3,426,441 to 1 per 15,570) and 0 per 67,438 MMR + V doses (1 per 18,282).

Dr. Klein reports receiving research support from Merck & Co, Novartis, GlaxoSmithKline, Pfizer, and Sanofi-Pasteur. Dr. Sawyer has disclosed no relevant financial relationships.

Pediatrics. Published online April 2, 2012. Full text

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