Measles and rubella seroprevalence among adults in Georgia in 2015: helping guide the elimination efforts

A large-scale measles outbreak (11 495 reported cases, 60% aged ≥15 years) occurred in Georgia during 2013–2015. A nationwide, multistage, stratified cluster serosurvey for hepatitis B and C among persons aged ≥18 years conducted in Georgia in late 2015 provided an opportunity to assess measles and rubella (MR) susceptibility after the outbreak. Residual specimens from 3125 participants aged 18–50 years were tested for Immunoglobulin G antibodies against MR using ELISA. Nationwide, 6.3% (95% CI 4.9%–7.6%) of the surveyed population were seronegative for measles and 8.6% (95% CI 7.1%–10.1%) were seronegative for rubella. Measles susceptibility was highest among 18–24 year-olds (10.1%) and declined with age to 1.2% among 45–50 year-olds (P < 0.01). Susceptibility to rubella was highest among 25–29 year-olds (15.3%), followed by 18–24 year-olds (11.6%) and 30–34 year-olds (10.2%), and declined to <5% among persons aged ≥35 years (P < 0.001). The susceptibility profiles in the present serosurvey were consistent with the epidemiology of recent MR cases and the history of the immunization programme. Measles susceptibility levels >10% among 18–24 year-olds in Georgia revealed continued risk for outbreaks among young adults. High susceptibility to rubella among 18–34 year-olds indicates a continuing risk for congenital rubella cases.