The Immunogenicity and Safety Profile for KM-248, a Combined Measles, Mumps, and Rubella Vaccine, and Its Noninferiority to the Measles Vaccine in Healthy Japanese Children: a Phase 3 Randomized Multicenter Single-Blind Clinical Trial.

The domestic combined measles-mumps-rubella (MMR) vaccine was withdrawn in Japan in 1993 following an outbreak of aseptic meningitis attributed to the mumps component of the cocktail. KM-248 is an MMR vaccine (M-M-RII), manufactured by Merck & Co., Inc. (Kenilworth, NJ, USA) and registered and approved in 74 countries, but which has not been approved in Japan. This multicenter, randomized, single-blind study, was designed to evaluate the noninferiority of the KM-248 measles component in terms of immunogenicity when compared to the control measles vaccine already approved in Japan and the seroconversion rates for these three viruses following KM-248 administration. Vaccination with KM-248 in children aged 12-90 months (n = 178) induced robust immune responses to measles, mumps, and rubella viruses. The seroconversion rate for the measles virus by the measles component of KM-248 (n = 172) was shown to be non-inferior to that of the control measles vaccine (n = 85). No serious adverse reactions, such as aseptic meningitis or anaphylaxis, were observed. Fever is one of the most common adverse reactions associated with vaccination and was observed in approximately half of the participants. KM-248 administered to healthy Japanese children aged between 12 and 90 months demonstrated a comparable safety and efficacy profile to the control vaccine.