A variety of disorders have been attributed to measles-mumps-rubella (MMR) vaccination, but serious adverse events that are causally linked to MMR vaccination are infrequent, according to a study of all MMR vaccinations in Finland over a 14-year period. The analysis showed that the risks associated with MMR vaccination were greatly outweighed by the risk of acquiring measles, mumps, or rubella.

Among 1.8 million patients receiving a total of almost three million vaccine doses from 1982 through 1996, there were 173 serious reactions that were thought to be attributable to MMR vaccination. Serious reactions were those that were potentially life threatening, triggered a potentially chronic disease, or resulted in hospitalization.

The 173 reactions consisted of 77 neurologic reactions (including seizures, epilepsy, encephalitis, and meningitis), 73 allergic reactions (including anaphylaxis, urticaria, and asthma), 22 miscellaneous reactions (for example, pneumonia, otitis media, orchitis, diabetes mellitus, and others), and one death resulting from aspiration of vomit induced by acute gastritis. Febrile seizure was the most common reported reaction.

However, 45% of the 173 reactions analyzed were determined by the researchers to be unrelated to MMR vaccination, yielding an incidence of serious adverse events possibly related to the vaccine of 5.3 per 100,000 vaccinees (3.2 per 100,000 vaccine doses).

Patja A, et al. Pediatr Infect Dis J 2000;19(12):1127-35.