What antibody response does Priorix induce in previously seronegative children aged 12 months to 2 years?

In previously seronegative children aged 12 months–2 years, one Priorix dose induced measles, mumps and rubella antibodies in 98.1%, 94.4% and 100%, respectively; two-year seroconversion rates were 93.4%, 94.4% and 100%, respectively, but protective efficacy data are unavailable and field studies suggest lower mumps effectiveness than seroconversion rates.