Clinical trials show similar safety outcomes including febrile convulsion rates for GSK's and Merck's measles-mumps-rubella (MMR) vaccines.

Combined measles-mumps-rubella (MMR) vaccines produced by GSK (GSK-MMR) and Merck (Merck-MMR) have demonstrated effectiveness and an acceptable safety profile, as documented over decades of post-licensure use in various regions worldwide. In the United States, 2 doses of the MMR vaccine are recommended at the ages of 12-15 months and 4-6 years. All-cause febrile convulsions have the highest incidence at 12-18 months of age, when the first MMR vaccine dose is administered. Because febrile convulsions can also occur rarely after MMR vaccine administration, we reviewed safety data of the GSK-MMR compared to the Merck-MMR vaccine from 4 clinical trials that evaluated a first dose in 12-15-month-olds and 2 clinical trials that evaluated a second dose in ≥4-year-olds. Overall frequencies of febrile convulsions were ≤0.4% across studies and vaccine groups. The frequency of febrile convulsions occurring 7-10 days post-vaccination with the GSK-MMR vaccine (5.7/10,000) was generally consistent with previously published data. The other safety outcomes were similar between the GSK-MMR and Merck-MMR vaccines in both age groups. Hence, as recommended by the Advisory Committee on Immunization Practices, the GSK-MMR vaccine can also be used for routine immunization of children according to the current immunization schedule in the United States to prevent MMR.