Ongoing measles and rubella transmission in Georgia, 2004-05: implications for the national and regional elimination efforts

Abstract

Background: In 2004-05, Georgia experienced large-scale concurrent measles and rubella outbreaks. We analysed measles and rubella epidemiology in Georgia to describe disease trends, determine the cause of the outbreaks, identify challenges to achieving disease elimination goals and propose interventions to overcome them.

Methods: We reviewed national measles and rubella surveillance and vaccination coverage data, focusing on the 2004-05 outbreaks, and conducted a measles vaccine effectiveness (VE) study using data from a 2004 school-based outbreak.

Results: Before 2004, the last large measles outbreak after measles vaccination was introduced (in 1966) in Georgia, was in 1988 (incidence rate, 36/100 000); the highest year for rubella was 1985 (110/100 000). During 2004-05, 8391 measles cases and 5151 rubella cases were reported (most of them diagnosed clinically). Of 358 suspected measles cases tested, 181 (51%) were positive for measles-IgM antibody; of 240 suspected rubella cases tested, 50 (21%) were positive for rubella-IgM antibody. Over 90% of measles cases were in persons born after 1979; 90% of rubella cases were in persons born after 1987. Approximately 41% of measles cases and 88% of rubella cases were unvaccinated. Estimated measles VE (>/=1 vs 0 doses) was 86% (95% CI, 58-96%).

Conclusions: The outbreak likely resulted from failure to vaccinate rather than vaccine failure. Susceptible persons likely accumulated due to the long absence of large outbreaks and decreased coverage after the collapse of Soviet Union. To interrupt measles and rubella transmission in Georgia and achieve disease elimination goals by 2010, supplementary immunization activities should target children and young adults.