Impact of rubella vaccination strategy on the occurrence of congenital rubella syndrome

Abstract

Routine rubella vaccination was introduced in Paraíba, northeastern Brazil, through a catch-up campaign targeting children aged 1-11 years, in 1998. A campaign among women of childbearing age was conducted in 2001. We describe the epidemiology of rubella and congenital rubella syndrome (CRS) in the state of Paraíba between 1999 and 2005. Rubella and CRS surveillance data for the 1999-2005 period were analyzed. Suspected cases of rubella were confirmed by laboratory findings, epidemiological link, or clinical data. International standardized CRS definitions were used. Of 5,924 suspected cases of rubella between 1999 and 2005, 1,266 (21%) were confirmed, 766 (61%) by laboratory findings. During a rubella epidemic in 2000 (18.8/100,000), the incidence among individuals aged 14-19 years (42/100,000) had a fourfold increase relative to children aged 1-13 years (95% confidence interval = 3.2-5.1). The overall rubella incidence was 0.9/100,000 in 2005. Of 177 suspected cases of CRS between 1999 and 2005, 167 (94%) were tested for IgM. Of 14 (8%) laboratory confirmed cases of CRS, 12 (86%) were born in 2001, with an incidence of 0.2/100,000 children aged less than 1 year. The 1998 rubella vaccination campaign was insufficient to prevent an outbreak among young adults in 2000, with a high CRS incidence in 2001. Between 2002 and 2005 the incidence of rubella and CRS decreased; however, high routine vaccination coverage and high-quality surveillance remain critically important to achieve CRS elimination by 2010.