Historical analysis of birth cohorts not vaccinated against rubella prior to national rubella vaccination campaign, Brazil.

BACKGROUND Brazil conducted mass rubella vaccination campaigns to meet disease elimination goals by 2010. An analysis of rubella vaccination opportunities was conducted to target population groups with concentrations of unvaccinated individuals. METHODS Rubella vaccination strategies for all 27 states were reviewed between 1992 and 2006. Yearly vaccination coverage was calculated by dividing number of doses of measles-rubella or measles-mumps-rubella vaccines administered by census estimates of target populations. For annual birth cohorts (1967-2005), percentages of persons not vaccinated prior to 2007 were estimated by subtracting the highest coverage obtained in any vaccination strategy (routine or campaign) from 100%. Cohort analysis results were compared with rubella incidence by population group. RESULTS An estimated 28.9 million males and 7.7 million females aged 2-40 years in 2007 remained unvaccinated against rubella, corresponding to 43.0% of males and 11.5% of females of these ages in Brazil. The highest percentages of unvaccinated birth cohorts (93.6%-98.1%) were identified among males aged 26-40 years. In rubella outbreaks reported during 2007, the highest disease incidence (22 cases per 100000 population) occurred among males aged 20-29 years. CONCLUSIONS Analysis of rubella vaccination opportunities identified concentrations of unvaccinated adults and adolescents for targeting mass vaccination to eliminate rubella and congenital rubella syndrome in Brazil.