Control of epidemic meningococcal meningitis by mass vaccination. I. Further epidemiological evaluation of groups A and C vaccines in northern Nigeria.

Mass vaccination campaigns were mounted by several state governments in the northern Nigerian sector of the African meningitis belt. Bivalent groups A and C polysaccharide vaccines were used. The results of these campaigns in four of the states which are adjacent to each other are presented and assessed. A total of 7535350 persons in the four States, Bauchi, Borno, Gongola and Plateau, were given the vaccine over a period of 4 years (1978-1981). There was a decline in the overall number of cases reported as well as in the number of deaths in the area, where, since 1978, there has not been an epidemic of meningococcal meningitis. Variations were observed among the states which vaccinated over 50% of their populations and had many fewer cases than those which did not. These results show that mass vaccination is an effective means of preventing outbreaks of meningococcal meningitis and may lead to eradication of the disease.