Immunogenicity of a serogroup B meningococcal vaccine against multiple Neisseria meningitidis strains in infants.

BACKGROUND: The serogroup B meningococcus is responsible for the majority of cases of meningococcal disease in temperate countries. Infants and young children <2 years of age are at greatest risk of disease. This study assessed the immunogenicity in infants of a serogroup B meningococcal outer membrane protein vaccine that has been used extensively in disease outbreaks in Cuba and several Latin American countries and shown to be efficacious in teenagers. METHOD: One hundred five healthy infants entering the routine vaccination schedule in Havana, Cuba, were given either 2 or 3 doses of the serogroup B meningococcal vaccine VA-MENGOC-BC at 3.5, 5.5 and 7.5 months of age. Immune response pre- and postvaccination was determined by the conventional serum bactericidal assay (SBA), a more sensitive novel whole blood bactericidal assay (WBA) and immunoglobulin ELISA. RESULTS: In 52 and 46% of infants >50% killing of the vaccine serogroup B strain (B:4:P1.19,15) and serogroup C strain, respectively, was demonstrated by the WBA after 2 doses of the vaccine. Serum bactericidal activity (4-fold increase in titer) was induced in only 27% against the vaccine serogroup B strain and in 14% against the serogroup C strain. The changes in WBA and SBA were mirrored by the serogroup B and C immunoglobulin ELISA. Cross-reactive immunogenicity against other (heterologous) serogroup B strains was demonstrated for one of the four further strains assessed by WBA. By age 16 to 18 months SBA, WBA and ELISA responses had declined considerably. The addition of a third dose of vaccine did not appear to significantly influence immunogenicity at 17 months of age. CONCLUSION: The serogroup B outer membrane protein vaccine VA-MENGOC-BC induces a demonstrable immune response in infants against both the serogroup B vaccine strain and against a serogroup C strain. Cross-reactive immunogenicity against other (heterologous) serogroup B strains is limited in this age group.

Immunogenicity of two efficacious outer membrane protein-based serogroup B meningococcal vaccines among young adults in Iceland.

Serum bactericidal activity (SBA) and ELISA antibody levels elicited by two efficacious serogroup B meningococcal vaccines were measured in a controlled trial involving 408 15- to 20-year-olds. Subjects were given two doses at a 6-week interval of a serogroup B or control vaccine. Response was defined as > or = 4-fold rise in antibody level. After two doses of the Finlay Institute (Havana) vaccine at 12 months, the proportions of SBA and ELISA responders were not different from those of the control group (15% and 17% [vaccine] vs. 13% and 9% [control], P > .05). After two doses of the National Institute of Public Health (Oslo) vaccine, there were more SBA and ELISA responders than in the control group (47% and 34% [vaccine] vs. 10% and 1% [control]) or the Finlay Institute vaccine group (P < .05 for both). SBA and ELISA may be insensitive correlates for protective efficacy for some outer membrane protein-based serogroup B meningococcal vaccines.

Vaccine against group B Neisseria meningitidis: protection trial and mass vaccination results in Cuba.

The Cuban vaccine, first in the world with proven efficacy against group B-caused disease, is based on outer membrane proteins from B meningococci capable of inducing long-lasting and high-titered bactericidal antibodies in humans. This bactericidal activity has a wide spectrum against all pathogenic group B Neisseria meningitidis tested. A randomized, double-blind controlled trial of the vaccine efficacy was performed during 1987-1989 with 106,000 10-14 years old students from 197 boarding schools in seven provinces. The efficacy obtained was 83% (chi 2, p less than 0.002; Fischer exact, p less than 0.001). In a second field trial including 133,600 persons from 5 months to 24 years of age in Ciego de Avila province (30 cases/10(5) inhabitants, the highest incidence rate in Cuba) by comparing vaccinated and non-vaccinated population after 2.5 years of observation and careful follow-up, the efficacy and safety was confirmed. Because of these results and because of the very low reactogenicity of the vaccine, the Ministry of Public Health took the advice of the Scientific Council to vaccinate all children between 3 months and 6 years of age in the most affected provinces. No severe or long lasting reactions to the vaccine were observed after the millions of doses administered. The efficacy of vaccination varied in the provinces between 83% and 94%, among age groups ranging from 3 months and 20 years. After 3 years of massive application no severe reactions occurred and one of the most severe epidemics has been practically eradicated.