Serogroup B Neisseria meningitidis is the most common cause of epidemic meningococcal disease in developed countries. Until recently no vaccine has been available for prevention of infection with this organism. In an attempt to control epidemic serogroup B meningococcal disease in greater Sao Paulo, Brazil, during 1989 and 1990, a Cuban-produced outer-membrane-protein-based serogroup B meningococcal vaccine was given to about 2.4 million children aged from 3 months to 6 years. We have done a case-control study to estimate the efficacy of the vaccine in greater Sao Paulo. Microbiologically confirmed cases of serogroup B meningococcal disease were identified through hospital-based surveillance. Controls were matched by neighbourhood and age. Vaccination status was confirmed by inspection of vaccination cards. Between June, 1990, and June, 1991, 112 patients and 409 matched controls with confirmed vaccine status were enrolled. Estimated vaccine efficacy varied by age: 48 months or older = 74% (95% Cl 16 to 92%), 24 to 47 months = 47% (-72 to 84%), and less than 24 months = -37% (< -100 to 73%). Our results suggest that the Cuban-produced vaccine may be effective for prevention of serogroup B meningococcal disease in older children and adults.
PIP: In 1990, researchers compared data on 112 3 month-6 year old children who received a Cuban produced, outer-membrane-protein-based serogroup B meningococcal vaccine (cases) and lived in greater Sao Paulo, Brazil with data on 409 age and neighborhood matched controls to determine the protective efficacy of the vaccine against serogroup B meningococcal disease (Neisseria meningitidis). Health workers began administering the vaccine in 1989 to control an epidemic of serogroup B meningococcal disease in the area. In fact, in mid-1989 and early 1990, the rates of serogroup B meningococcal disease in 1-6 year old children in Sao Paulo were 2.07/100,000 and 2.3/100,000, respectively. Even though only 44% of serogroup B meningococcal isolates corresponded with the vaccine type strain (B:4:P1:15), many isolates had man of the same serotype or subtype antigens as the vaccine type strain. Thus the vaccine was able to protect against some other serogroup B meningococcal strains other than the vaccine type strain. Vaccine efficacy for 4-year old children was 74%, but was much lower for 24-47 month old children (47%) and 24-month old children (-37%). The change in the log odds ratio for vaccination by age was linear and significant (p=.057). The researchers suggested that poor vaccine efficacy among younger children may reflect a need for more boosting to achieve protective levels of immunity. The results showed that the Cuban-produced vaccine could contribute to control of outbreaks of serogroup B meningococcal disease by protecting older children and adults from the disease. Researchers need to conduct additional studies of the vaccine and other possible serogroup B meningococcal vaccines.