Clinical Trial of Measles and Rubella Combined Vaccine Produced by POLYVAC in Vietnam

A clinical trial of measles and rubella combined vaccine(MR: MRVAC) produced by POLYVAC was conducted in Vietnam in 2016. A total of 756subjects were enrolled, and 504 were allocated to MRVAC and 252 to control MR vaccinegroups. Paired sera were obtained in 733, and the number of subjects was 403 aged1 - 2 years, 164 aged 2 - 18 years, and 166 aged 18 - 45 years.Antibodies against measles and rubella viruses were evaluated by EIA. Most subjectshad been immunized with a single dose of Expanded Programme on Immunization (EPI)measles vaccine at 9 months of age. Only 41 of 403 subjects aged 1 - 2 yearswere negative for measles antibody before vaccination, and all became seroconverted.A serological response of more than a 2-fold increase against measles was notedin 214 (47%, 95% CI; 42.4% - 51.6%) of 458 initially seropositive individuals immunized with MRVAC and65 (28%, 95% CI; 22.3% - 33.8%) of 234 in the control group, and geometric mean titer (GMT) after vaccinationwas 25.49-5.60 in MRVAC and 25.03-5.24 in control group. Seroconversion against rubella virus after immunization with MRVACwas noted in 267 (98.5%, 95% CI; 97.1% - 100%) of271 initially seronegative subjects, similar to that after immunization with controlgroup. GMT after immunization with MRVAC was 24.88-5.11 significantlylower than that after immunization with control vaccine (25.59-5.80).Most subject ≥ 2 years of age had rubella antibody because of MR vaccination campaign andno significant serological response was observed in initially seronegatives. MRVACwas highly immunogenic and safe vaccine and the domestic production of MR vaccinewould contribute to realizing the goal of eliminating measles and rubella.