Adverse events(AE) associated with vaccination have not been systematically monitored in Korea. But since 1994, several deaths after inactivated mouse brain derived Japanese encephalitis vaccine injection arouse the safety problem of immunization in the public, and a evaluation of vaccination program including the effectiveness and safety problem had been started. We have been using MMR vaccine containing Japanese mumps vaccine strains, which are known to be associated with the high rate of adverse events including aseptic meningitis, for the last decade.

We conducted a prospective study of vaccine adverse events associated with MMR vaccine through a tracking system using telephone calls. We followed up 7,594 cases of MMR vaccinees.

Reported adverse events included fever, couvulsion, parotitis, and aseptic meningitis. Nine cases of parotitis and seven cases of aseptic meningitis were recognized during follow up period. The incidence of both parotitis and aeptic meningitis was 85.1/ 10⁵, for Urabe mumps strain. For Hoshino strain, the incidence of parotitis and aseptic meningitis was 158.0/ 10⁵ and 94.8/ 10⁵, respectively.

The incidence of adverse events was to be a higher than that of natural infection in Korea and was comparable to the results of studies done in other countries.