Epidemic of meningococcal meningitis in Bamako, Mali: epidemiological features and analysis of vaccine efficacy.

Many studies have demonstrated the efficacy of meningococcal vaccine in nonepidemic meningococcal meningitis, but few have examined its efficacy in epidemic conditions. The effects of the vaccine on the course of a meningococcal meningitis epidemic in Bamako, Mali, between January and April, 1981, were studied. The vaccine was effective in limiting further spread of the epidemic. The attack rate among those who received vaccine was lower than that in the unvaccinated (0.7/10 000 vs 4.7/10 000), and the case-fatality rate among vaccinees in whom meningitis developed was lower than that of the unvaccinated. Routine vaccination against meningococcal meningitis in Africa may be impracticable owing to the cost, the relatively short duration of effectiveness, and the irregular occurrence of epidemics. Vaccination early in the course of an epidemic, however, appears to be a useful and practicable method of limiting the spread of disease.