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 c ompare the reactogenicity and immunogenicity of a new measles, mumps and ru bella (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 subject s had previously received Merck MMR in the first year of life. In initially , seronegative subjects, all subjects receiving the Merck MMR vaccine had s eroconverted with respect to measles (10/10 subjects), mumps (38/38) and ru bella (4/4). Of the subjects receiving SB MMR, 6/7 seroconverted with respe ct 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 (G MVs) between groups. In initially seropositive subjects, a higher anti-mump s immune response rate was observed in the SB MMR group (59.3%) compared wi th the Merck MMR group (24.1%.). Higher post-vaccination anti-mumps and ant i-rubella GMVs were observed in the group receiving SB MMR (p < 0.007), whe reas higher anti-measles GMVs were observed in the Merck MMR group (p = 0.0 013). 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%). Inci dences of systemic reactions were similar between groups.