Immunogenicity and safety of an investigational quadrivalent measles, mumps, rubella, and varicella vaccine in children aged 4-6 years: A phase II, randomized, multi-country trial.

Two-dose childhood vaccination against measles, mumps, rubella, and varicella is widely recommended. Quadrivalent (MMRV) vaccines can be used for one or both immunizations against these diseases. In some countries, e.g. the United States, only one MMRV vaccine is licensed. Availability of another MMRV vaccine could strengthen supply resilience, optimal vaccine coverage, and disease control. In this phase II, single-blind, multi-country study, healthy children aged 4-6 y, previously primed with a first dose of any combination of measles/mumps/rubella/varicella-containing vaccine(s) in their second year of life, were randomized 2:2:2:1:1 to receive one dose of a GSK investigational MMRV (MMRVNS; three formulations) or a licensed MMRV vaccine (two lots). Immunogenicity was assessed at Day 43 post-vaccination. Adverse events (AEs) were recorded up to Day 4 (solicited administration-site and systemic AEs), Day 43 (solicited systemic and unsolicited AEs), and Day 181 (serious AEs [SAEs]) post-vaccination. Of 801 participants enrolled, 796 were vaccinated and 765 completed the study. Antigen-specific antibody geometric mean concentrations and seroresponse rates were generally comparable between MMRVNS (regardless of formulation) and MMRV recipients. Administration-site pain (29.0%-39.0% of participants) and systemic drowsiness (9.0%-15.9%) were the most common solicited AEs. Unsolicited AEs (mostly upper respiratory tract infections) were reported in 18.5%-27.2% of participants. At least one SAE (none considered vaccine-related) occurred in each group. Except for one reported fatality, all SAEs resolved. Compared to the licensed standard-of-care MMRV vaccine, the investigational MMRVNS formulations generated comparable immune responses and had a similarly acceptable safety profile, when administered as second dose. These results support further clinical development of MMRVNS.