Seroprevalence of measles, mumps and rubella among young adults, after 20 years of universal 2-dose MMR vaccination in Israel.

Evidence-based vaccination policy is important for the global and local efforts of achieving control over measles. In 2007, the first Israeli birth cohort to be twice vaccinated during childhood with Measles-Mumps-Rubella vaccine reached adulthood. In parallel, Israel experienced its largest measles outbreak since 1994. We aimed to assess the seroprevalence of measles IgG antibodies and concordance with rubella and mumps seroprevalence among young Israeli adults born 1988-9 in comparison to previous birth cohorts, in order to inform evidence based prevention policy. We conducted a seroprevalence study of IgG antibodies among 439 Israeli adults born in 1988-9, based on a representative sample of sera collected at age 18-19 upon recruitment to mandatory military service in 2007. In total, 85.7% were seropositive for measles as compared with 95.6% in the 1996 recruitment (P < 0.001). The absolute decline was significant both for males (8.8%, P = 0.001) and females (12.1%, P < 0.001). There were no significant differences in seropositivity by gender, years of education, country of birth or smoking status. Rubella seropositivity among measles seropositives was 90.4%, significantly (P < 0.001) higher than 72.1% among measles seronegatives. Mumps seropositivity among measles seropositives was 87.0%, significantly (P < 0.001) higher than 62.3% among measles seronegatives. Results were similar for Israeli-born only. Our findings indicate that measles seroprevalence decreased after the last change in vaccination policy and reach sub-optimal level. Until global eradication is reached, a proactive vaccination program to supplement routine childhood vaccination program should be considered in Israel and in other countries.