Background: This clinical trial was conducted to demonstrate that each of 3 consistency lots of a combined measles, mumps, rubella and varicella vaccine (MMRV) would be well tolerated, induce clinically acceptable and similar immune responses to each antigen and induce immune responses similar to measles, mumps and rubella vaccine (MMR) administered concomitantly with varicella vaccine (V). An additional objective was to evaluate the persistence of antibodies 1 year postvaccination.
Methods: Study participants 12 to 23 months of age received a single injection of either one of 3 consistency lots of MMRV or MMR + V administered at separate injection sites.
Results: A total of 3,928 healthy children were enrolled at study sites in the United States and Canada. Immune responses to measles, mumps, rubella and varicella in children immunized with each of 3 lots of MMRV were similar and the combined response to all 3 lots was comparable to that of the control group. The 1-year antibody persistence rates for measles, mumps, rubella and varicella viruses were each greater than 95% and comparable among the recipients of the 3 consistency lots of MMRV and the control group. All vaccines were generally well tolerated during the 42 days after vaccination and the overall incidence of adverse experiences was comparable between recipients of MMRV and MMR + V. Rates of fever (temperature >or=38.9 degrees C oral equivalent or tactile) were greater in recipients of MMRV than in recipients of MMR + V (39.1% versus 33.1%, P = 0.001). Fevers were transient and there was no difference in the incidence of febrile seizures.
Conclusions: MMRV was generally well tolerated and had comparable immunogenicity and overall safety profiles to MMR + V administered concomitantly. Long-term persistence of antibodies after receipt of MMRV is expected based on similar antibody titers against all 4 antigens 1 year postvaccination compared with recipients of MMR and V.