This Phase II randomized trial compared a GSK investigational MMRV vaccine against a licensed MMRV vaccine. The study included 801 healthy children aged 4 to 6 years who had previously received a dose of a measles, mumps, rubella, or varicella vaccine in their second year of life. Participants were enrolled across multiple countries.
Researchers assessed immune responses at Day 43 after vaccination. They also tracked side effects up to Day 181. The results showed that antibody levels and seroresponse rates were comparable between the investigational vaccine and the licensed vaccine, regardless of the specific formulation used.
Safety data indicated administration-site pain occurred in 29.0% to 39.0% of participants, while drowsiness was reported in 9.0% to 15.9%. Unsolicited adverse events, mostly upper respiratory tract infections, affected 18.5% to 27.2% of participants. At least one serious adverse event occurred in each group, but none were considered vaccine-related except for one reported fatality. All serious adverse events resolved.
The study supports further clinical development of the investigational MMRVNS vaccine. Readers should note this is a Phase II trial with a sample size of 796 vaccinated participants. The findings are based on immunogenicity and safety data collected at specific time points.