A study of two types of vaccines that contain measles in children has found them to have the same low rates of adverse reactions. The study looked at data for seven types of adverse reactions to the vaccines, and seizures and fever. The two vaccines were the combination vaccine against measles, mumps, rubella, and varicella (MMRV) and the combination vaccine against measles, mumps, and rubella (MMR) plus a separate vaccine against varicella (V) administered the same day.
Varicella is chickenpox, while rubella is German measles.
The purpose of the study was to determine which vaccination pattern had the fewer adverse reactions. Vaccines that contain measles have been associated in rare instances with several types of adverse reactions, including fever and seizure.
Because vaccines containing measles are associated with a risk of a toddler having fever and seizures, researchers with the Kaiser Permanente Vaccine Study Center in Oakland investigated whether the single MMRV vaccine carried more risk than administering MMR and V administered as two shots. They found there were no new safety concerns with either, nor were any found with either of the vaccines alone.
The study evaluated data from a total of 123,200 doses of MMRV and 584,987 doses of MMR and V that were administered to toddlers from January 2000 through June 2012.
There was no increased risk found for neurological, immune, or blood adverse reactions such as anaphylaxis (allergic reaction), arthritis, meningitis or encephalitis. There were no incidents of some of the adverse reactions which were looked for by the study.
The study confirmed that both MMRV and MMR and V are associated with fever and a small risk of a seizure due to fever within 7 to 10 days after vaccination among 1-year-old children. MMRV has a higher risk of this than the separately administered vaccines. The risk of a seizure due to fever after vaccination is about one per 1,000 injections.
"These findings indicate that even if an increased risk for these outcomes exists, the risk is low and rare. This should reassure parents that these outcomes are unlikely after either vaccine," said Nicola P. Klein, MD, PhD, co-director of the Vaccine Study Center and an author of the study. "This level of safety monitoring for vaccines can give the public confidence that vaccine surveillance is ongoing and that if a safety problem existed, it would be detected."