Phase III, open-label, single-arm study of a new MMR vaccine (JVC-001); measles AIK-C, mumps RIT 4385, rubella Takahashi, as a second vaccine dose in healthy Japanese children aged 5-6 years.

Purpose: This Phase III, multicenter, open-label, single-arm study evaluated the safety and immunogenicity of the measles-mumps-rubella (MMR) combined vaccine, JVC-001, as a second MMR vaccination.

Methods: Healthy Japanese children aged 5-6 years received a single dose of JVC-001 following a first measles, mumps, and rubella vaccination (measles-rubella bivalent and mumps monovalent vaccine [Hoshino or Torii strain] or JVC-001) or the MMR vaccine received between ages 1 to <4 years. Immunogenicity was evaluated using antibody titers before and after vaccination (Day 1/Day 43). The primary endpoint was the seroprotection rate of antibody titers against each virus; geometric mean titer (GMT) was also evaluated. Adverse events (AEs) and adverse drug reactions (ADRs) were monitored.

Results: One-hundred participants completed the study. The seroprotection rate of antibody titers against measles, rubella, and mumps virus (genotype D) were 100.0 % (95 % confidence interval [CI] 96.4 %, 100.0 %), 100.0 % (95 % CI 96.4 %, 100.0 %), and 100.0 % (95 % CI 96.3 %, 100.0 %), respectively. GMT (fold) increases (Day 1 to Day 43) were 16.0 to 55.7 for measles virus, 35.5 to 99.0 for rubella virus, and 25.7 to 89.5 for mumps virus (genotype D). Solicited ADRs occurred in 40.0 % of participants (injection site, 34.0 %; systemic, 13.0 %).

Conclusions: The second MMR vaccination with JVC-001 demonstrated sufficient antibody coverage against all three viruses; the safety profile was tolerable.

Clinical Trial Registration: jRCT2080225022.