Assessment of the Direct Effectiveness of BC Meningococcal Vaccine in Rio de Janeiro, Brazil: A Case-Control Study

Abstract

Meningococcal disease is still a serious public health problem in many countries. A vaccine produced by Cuba was the first product against B meningococcus available on a large scale. In an attempt to control the increasing incidence of this serogroup in greater Rio de Janeiro, Brazil, the vaccine was used in 1990 in children aged 6 months–9 years. About 1.6 million children were vaccinated. In order to assess the direct effectiveness of the vaccine in preventing disease, we conducted a case-control study during the first year after vaccination. Using a hospital-based census, we selected all children hospitalized with meningococcal disease and sampled the control group among children hospitalized with other types of meningltis. Vaccine effectiveness was estimated from the relationship, 1 – OR, where OR (odds ratio) was the exponential of the logistic regression coefficient for the association between meningococcal disease and prevlous vacclnation. A total of 275 cases and 279 controls were selected between September 1990 and October 1991. The summary adjusted measure of protection against serogroup B was 54% (95% confidence interval [Cl]: 20–74%). Estimated protection varied among different age strata and place of residence, being high among children aged >4 years, 71% (95% CI : 34–87%), and among those who lived in the City of Rio de Janeiro, 74% (95% Cl: 42–89%). The results suggest that the vaccine produced by Cuba may offer protectection against serogroup B meningo-coccal disease, but its effects may not be homogeneous.