In 2005, the Food and Drug Administration approved a combo shot for all four—the MMRV vaccine—which provided an alternative to the previous method of giving an MMR vaccine dose (against measles, mumps, and rubella) plus a separate varicella vaccine dose at the same time. (This vaccination strategy is shorthanded as MMR + V.) Thus, the MMRV combo shot meant one fewer shot for children. But, in 2008, post-market data suggested that the MMRV shot might have a slightly higher risk of causing febrile seizures (seizures associated with fevers), which is a very low risk with the MMR + V separate shots.
Febrile seizures are a somewhat common reaction in
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