Rubella seroprevalence in the first birth cohort reaching fertility age after 20 years of two dose universal vaccination policy in Israel

Background: A national program of a 2-dose universal childhood MMR vaccination policy has been in effect in Israel since 1988. As the 1988 birth cohort reached fertility age, questions regarding immunity against rubella were raised. Objective: To assess the seroprevalence of rubella IgG antibodies among young Israeli adults born after 1987 in comparison to previous birth cohorts, in order to determine evidence based policy for prevention of rubella and congenital rubella syndrome. Methods: We conducted a seroprevalence study of rubella IgG antibodies among 416 Israeli adults (42.5% females) born in 1988-1989, based on a representative sample of sera collected at age 18-19 upon recruitment to mandatory military service in 2007. Results: In total, 87.7% were seropositive (>15. IU/ml) as compared with 84.8% in the 1999 recruitment (P=0.26) and 93.4% in 1987 (P=0.004). Yet there was a difference by gender. The proportion of seropositives among female young adults (92.7%) was significantly lower as compared to those measured in the 1999 (99.2%, P=0.001) and 1987 (99.0%, P=0.006) recruitments. The proportion of seropositives among males (84.1%) was significantly higher as compared to those measured in 1999 (73.0%, P< 0.001) but similar to those of 1987 (88.8%, P=0.13). Females born in the FSU were found to be high risk groups as 11.5% were seronegative. Conclusions: Our findings indicate that despite a successful program of congenital rubella syndrome prevention in Israel, there is a decline in seroprevalence among female young adults, especially immigrants from the FSU. A proactive catch-up program for females, especially for those of higher risk for susceptibility should be considered in Israel and in other countries.