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

Background: Brazil must conduct mass rubella vaccination campaigns to meet disease elimination goals by 2010.  An analysis of rubella vaccination opportunities was conducted to identify population groups with concentrations of unvaccinated individuals. 
Methods: Vaccination strategies for all 27 states were reviewed between 1992 and 2006.  Yearly vaccination coverage was calculated by dividing number of doses administered by census estimates of target population.  For annual birth cohorts (1927-2005), 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 percent.  Cohort analysis results were compared with rubella incidence by population group.
Results: An estimated 28.9 million males and 7.7 million females between the ages of 2 and 40 years in 2007 remained unvaccinated against rubella, corresponding to 43.0% of males and 11.5% of females of these ages in Brazil.  Highest percentages of unvaccinated birth cohorts (93.6%-98.1%) were identified among males 26-40 years of age.  In rubella outbreaks reported during 2007, the highest disease incidence (20 cases/100,000 population) occurred among males 20-29 years of age.
Conclusions: Analysis of rubella vaccination opportunities identified concentrations of unvaccinated adults and adolescents to be targeted in mass vaccination campaigns.