Immunogenicity and safety of two doses of tetravalent measles-mumps-rubella-varicella vaccine in healthy children

Background: Combination vaccines against common childhood diseases are widely used, provide an improved coverage, are more convenient and are more cost-effective than multiple injections. We conducted a study to evaluate the safety and immunogenicity of a combined measles-mumps-rubella-varicella (MMRV) candidate vaccine in comparison with the separate administration of licensed measles-mumps-rubella (MMR; Priorix) and varicella (V; Varilrix) vaccines. Methods: Healthy children 12-18 months of age received 2 doses of MMRV vaccine (3 lots) 6-8 weeks apart (MMRV group) or 1 dose of MMR vaccine administered concomitantly with 1 dose of varicella vaccine, followed by a second dose of MMR at 6-8 weeks later (MMR+V group). Local symptoms (redness, pain and swelling) were recorded for 4 days after vaccination, and fever (any, axillary temperature >= 37.5 degrees C or rectal temperature >= 38.0 degrees C; grade 3, axillary temperature > 39.0 degrees C or rectal temperature > 39.50 degrees C) was monitored daily for 15 days. Other adverse events were monitored for 6 weeks. Results: A total of 494 children were vaccinated (371 in the MMRV group and 123 in the MMR+V group. Two doses of MMRV vaccine were at least as immunogenic as 2 doses of MMR and 1 dose of varicella vaccine. After the second dose, all children had seroconverted to measles, rubella and varicella in both vaccine groups, and 98% versus 99% had seroconverted to mumps in the MMRV versus the MMR+V group, respectively. The MMRV vaccine did not induce an increased local or general reactogenicity compared with the separate administration, although a higher incidence of low grade fever was seen after the first dose in the MMRV group (67.7% after MMRV versus 48.8% after MMR+V; P < 0.05), this was not observed for grade 3 fever (11.6% after MNIRV versus 10.6% after MMR+V; P = 0.87). After the second dose, no differences in incidence of fever were found in either MMRV or MMR+V groups. Conclusion: Administration of 2 doses of the combined MMRV vaccine was as immunogenic and well-tolerated as separate injections of MMR and varicella vaccine.