Immunogenicity and safety of a varicella vaccine, Okavax, and a trivalent measles, mumps and rubella vaccine, MMR-II, administered concomitantly in healthy Filipino children aged 12-24 months.

ABSTRACT

This trial was conducted to assess the immunogenicity and safety of the varicella vaccine, Okavax, when administered concomitantly with the measles, mumps and rubella vaccine, MMR-II, to children aged 12-24 months. A total of 299 children were randomized into three groups, those receiving Okavax only, MMR-II only, or both vaccines concomitantly. Antibody titers were determined by ELISA in blood samples taken immediately before, and 6 weeks after, vaccination. Parents recorded local and systemic reactions. Okavax elicited similar varicella seroconversion rates (> or = 93.9%) and high GMTs when given alone or with MMR-II (99.6 and 95.7 mIU/ml, respectively). The seroconversion rates (measles and rubella 100%, mumps > or = 75.0%) and high GMTs elicited by MMR-II were not affected by concomitant administration of Okavax. The incidence of adverse events was similar whether MMR-II and Okavax were administered concomitantly or separately, and the majority of local reactions were mild and transient, with fever the most frequent systemic event in all groups. In conclusion, these results show that the immune response and the reactogenicity profile of Okavax and MMR-II were similar when given together or alone. Concomitant administration of these vaccines can therefore be recommended for children in their second year of life.