Two doses of a varicella-containing vaccine in healthy children <12 years are suggested to induce better protection than a single dose. Persistence of immunity against measles, mumps, rubella, and varicella as well as varicella breakthrough cases were assessed 3 years after two-dose measles, mumps, rubella, and varicella (MMRV) vaccination or concomitant MMR (Priorix™) and varicella (Varilrix™) vaccination. Four hundred ninety-four healthy children, 12-18 months old at the time of the first dose, received either two doses of MMRV vaccine (GlaxoSmithKline Biologicals) 42-56 days apart (MMRV, N = 371) or one dose of MMR and varicella vaccines administered simultaneously at separate sites, followed by another MMR vaccination 42-56 days later (MMR + V, N = 123). Three hundred-four subjects participated in 3-year follow-up for persistence of immunity and occurrence of breakthrough varicella (MMRV, N = 225; MMR + V, N = 79). Antibodies were measured by ELISA (measles, mumps, rubella) and immunofluorescence (varicella). Contacts with individuals with varicella or zoster and cases of breakthrough varicella disease were recorded. Three years post-vaccination seropositivity rates in subjects seronegative before vaccination were: MMRV-measles, 98.5% (geometric mean titer [GMT] = 3,599.6); mumps, 97.4% (GMT = 1,754.5); rubella, 100% (GMT = 51.9); varicella, 99.4% (GMT = 225.5); MMR + V-measles, 97.0% (GMT = 1,818.8); mumps, 93.8% (GMT = 1,454.6); rubella, 100% (GMT = 53.8); and varicella, 96.8% (GMT = 105.8). Of the subjects, 15-20% reported contact with individuals with varicella/zoster each year. After 3 years, the cumulative varicella breakthrough disease rate was 0.7% (two cases) in the MMRV group and 5.4% (five cases) in the MMR + V group.
Conclusion: Immunogenicity of the combined MMRV vaccine was sustained 3 years post-vaccination. (208136/041/NCT00406211).