Immunogenicity and reactogenicity of a new measles, mumps and rubella vaccine when administered as a second dose at 12 y of age.

An open randomized trial involving 301 subjects was conducted in order to compare the reactogenicity and immunogenicity of a new measles, mumps and rubella (MMR) vaccine, SB MMR, with those of a commercial MMR vaccine, Merck MMR, when given as a second dose to children at 11-12 y of age. All subjects had previously received Merck MMR in the first year of life. In initially seronegative subjects, all subjects receiving the Merck MMR vaccine had seroconverted with respect to measles (10/10 subjects), mumps (38/38) and rubella (4/4). Of the subjects receiving SB MMR, 6/7 seroconverted with respect to measles, 29/31 with respect to mumps and 3/3 with respect to rubella. No difference was seen in seroconversion rates or geometric mean values (GMVs) between groups. In initially seropositive subjects, a higher anti-mumps immune response rate was observed in the SB MMR group (59.3%) compared with the Merck MMR group (24.1%). Higher post-vaccination anti-mumps and anti-rubella GMVs were observed in the group receiving SB MMR (p < 0.007), whereas higher anti-measles GMVs were observed in the Merck MMR group (p = 0.0013). There was a lower (p = 0.013) incidence of pain at the injection site in subjects receiving SB MMR (20.1%) compared with Merck MMR (33.3%). Incidences of systemic reactions were similar between groups.