Update on Age-Specific Rubella Seropositivity Rates among Pregnant Women ۱۲ Years after Vaccine Introduction in Tunisia

Aims: Assessment of rubella immunity coverage relies on regular updates. This study aimed to determine the age-specific seropositivity rates among a large cohort of pregnant women approximately ۱۲ years after vaccine introduction in Tunisia, where serosurveys are both old and scarce. Materials & Methods: A prospective cohort study was conducted on pregnant women referring to the Maternity and Neonatology Center of Tunis in ۲۰۱۷. Eligible and consenting participants underwent blood sampling twice with a ۱۵-day interval to detect and measure rubella-specific IgG and IgM antibodies. Demographic and obstetric data were also gathered. Findings: A total of ۸۰۰ participants with a mean age of ۳۰.۶±۵ years (range: ۱۷-۴۸) were enrolled in this study. The overall seropositivity rate was ۹۰.۴% (n=۷۲۳) (۹۵%CI: ۸۸.۳-۹۲.۴). Also, ۷۷ (۹.۶%) (۹۵%CI: ۷.۶-۱۱.۷) participants were seronegative, among them ۳۶ cases were in the first trimester of their pregnancy. The WHO minimum rubella immunization threshold of ۹۵% was achieved for the first time in the ۱۲-year-old vaccination program target population (۹۶%) (۹۵%CI: ۹۲-۹۹.۸). No significant association was found between seropositivity rates and age, geographic origin, occupation, gestational age at the time of enrollment, parity, and abortion history (p> .۰۵), but a significant association was found with educational levels. Conclusion: Pregnant women vaccinated at the age of ۱۲ showed a high immunization rate. Next decades would witness the elimination of rubella virus circulation as well as congenital rubella syndrome.

Keywords:

Rubella virus , Epidemiology , Congenital infection , Immunity/Immunization