Meningococcal vaccine against serogroups A, C, Y and W-135: new preparation. Encouraging immunogenicity studies.

(1) Prevention of meningococcal meningitis is based on vaccination, and chemoprophylaxis in case contacts. The five main meningococcal serogroups known to be pathogenic for humans are A, B, C, Y and W-135. Their geographic distribution is variable. In France, two-thirds of cases are due to serogroup B, which is poorly immunogenic and for which there is no vaccine; the only licensed vaccine offers protection solely against serogroups A and C. (2) A meningococcal polysaccharide vaccine directed against serogroups A, C, Y and W-135 has been granted temporary authorization for use by pilgrims to Mecca and for case contacts. (3) The vaccine elicits antibodies against the four serogroups in most adults, at least in the short term. It is poorly immunogenic in children under two years of age, especially against serogroup C. (4) The preventive efficacy of the vaccine against meningitis due to serogroups Y and W-135 is not known, and few data are available on serogroups A and C. Protection has not been shown beyond two years after vaccination. At one year the vaccine provides about 95% protection against serogroup A and 65% against serogroup C. (5) Systemic and local reactions to vaccination with the four-valent vaccine appear to be acceptable. (6) In practice, for want of anything better, the four valent vaccine (A, C, Y and W-135) is better than the two-valent vaccine (A+C) for protecting pilgrims to Mecca and contacts of patients with serogroup A, C, Y or W-135 meningococcal infection.