Adverse Outcomes Unlikely After Measles, Mumps Vaccination

January 11, 2015
Eileen Oldfield Associate Editor

The 7 main adverse outcomes associated with 2 common childhood immunizations are highly unlikely to occur following vaccine administration.

The 7 main adverse outcomes associated with 2 common childhood immunizations are highly unlikely to occur following vaccine administration, according to the results of a long-term study published online on January 5, 2015, in Pediatrics.

Over a 12-year period, researchers from the Kaiser Permanente Vaccine Study Center evaluated 123,200 measles-mumps-rubella-varicella (MMRV) vaccine doses and 584,987 separately administered, same-day measles-mumps-rubella and varicella (MMR+V) vaccine doses given to children aged 12 to 23 months.

When the researchers compared the 2 vaccines, they found that the risks of immune thrombocytopenia purpura, anaphylaxis, ataxia, arthritis, meningitis/encephalitis, acute disseminated encephalomyelitis, and Kawasaki disease did not increase.

"In fact, there were few or zero events for several outcomes following vaccination,” noted lead study author Nicola P. Klein, MD, PhD, in a press release.

Additionally, the investigators found no new safety concerns associated with either vaccine.

“These findings indicate that even if an increased risk for these outcomes exists, the risk is low and rare,” Dr. Klein said in the press release. “This should reassure parents that these outcomes are unlikely after either vaccine.”

However, the research confirmed previously reported associations between both vaccines and fever and febrile seizure occurring 7 to 10 days after vaccination in patients aged 1 year. Nevertheless, such adverse events occur infrequently, at a rate of <1 febrile seizure occurring per 1000 injections.

“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,” Dr. Klein continued in the press release. “Our findings offer reassurance that adverse outcomes of measles-containing vaccines are extremely rare and unlikely, and that parents of 1-year-old children can choose MMR + V instead of MMRV vaccines to reduce the low risk of fever and febrile seizures.”