U.S. Health Officials Back Off Preference for New MMRV Vaccine

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The VSD then initiated a study of 43,353 children aged 12 to 23 months who received the MMRV vaccine and 314,599 children aged 12 to 23 months who received the MMR vaccine and varicella vaccine during the same visit, according to the CDC report.

"The preliminary results indicated a rate of febrile seizure of nine per 10,000 vaccinations among MMRV vaccine recipients compared with four per 10,000 vaccinations among MMR vaccine and varicella vaccine recipients," the CDC reported. "These results suggest that, in the 7-10 day post-vaccination period, approximately one additional febrile seizure would occur among every 2,000 children vaccinated with MMRV vaccine, compared with children vaccinated with MMR vaccine and varicella vaccine administered at the same visit."

On Feb. 27, the ACIP was informed about the heightened risk.

Febrile seizures are convulsions brought on by fever, usually from common childhood illnesses such as middle ear infections, viral upper respiratory tract infections and roseola. Although the seizures are distressing, children generally recover, according to the CDC.

"Practically speaking, it means little," said Dr. Paul A. Offit, director of the Vaccine Education Center and chief of infectious diseases at the Children's Hospital of Philadelphia. "The attributable risk of fever is still quite low. I think the committee thought the better part of valor was at least not to express a preference for one over the other. For the most part, MMRV is not particularly available, so there's little or no impact."

There is no data yet on the risk for febrile seizures after the second MMRV vaccine, which is given at 4 to 6 years of age, although previous research showed that the second dose is less likely to cause fever than the first.

The changes have nothing to do with a possible vaccination link to autism, Frenck said.

More information

The Vaccine Safety Datalink has more on vaccine and febrile seizures.