AGE-STRATIFIED SEROPREVALENCE OF MEASLES, MUMPS AND RUBELLA (MMR) VIRUS-INFECTIONS IN SWITZERLAND AFTER THE INTRODUCTION OF MMR MASS VACCINATION

We have performed age-stratified seroprevalence studies for MMR to eva luate these vaccinations. Serum samples submitted for diagnostic testi ng were randomly selected for unlinked anonymous panels. IgG antibodie s were tested by ELISA and indirect immunofluorescence. In the vaccina tion cohort (age 1.5 to 6.5 years), seroprevalence attained 80%. For m easles and mumps it continued to increase to 95%, while for rubella it declined transiently to 60% between 7 and 12 years of age. We observe d no differences according to gender in any age group in 1991-1992. (S emi)quantitative values of the IgG antibodies against all three viruse s increased during adolescence, suggesting wild virus circulation. In 1992, MMR vaccination has reached < 80% of the children during their s econd year of age. Due to previous monovalent measles and mumps vaccin ations in pre-school children and due to endemic and epidemic activity , particularly of mumps virus, a trough of the seroprevalence in adole scents was evident only for rubella. MMR vaccination campaigns perform ed at school since 1987 have increased seroprevalence in this populati on segment and have probably over-compensated for the expected shift t o the right of the seroprevalence curves. A more compulsive implementa tion of the recommended childhood vaccination schedule and continued e fforts at catchup vaccinations during school age especially for rubell a are necessary to avoid the accumulation of susceptible young adults during the forthcoming decades.