Immunogenicity, Safety of Measles-mumps-rubella-varicella Vaccine (MeMuRu-OKA) Compared to Priorix™ Given With Varilrix™

Since measles-mumps-rubella (MMR) and varicella vaccinations are established as routine childhood practice and often co-administered during the second year of life, a combined measles-mumps-rubella-varicella (MeMuRu-OKA) vaccine is fully justified. Such a combined vaccine was developed and extensively studied in susceptible children. In countries where varicella mass-vaccination is already implemented, a transition period is necessary as children who started with separate first-dose vaccinations of MMR and varicella will receive a single shot of the combined vaccine as the second dose. To account for those situations, this study will evaluate the effect of the combined measles-mumps-rubella-varicella vaccine given in place of separate MMR and varicella vaccines as a second dose.