Meningococcal Meningitis Outbreaks in the African Meningitis Belt After Meningococcal Serogroup A Conjugate Vaccine Introduction, 2011-2017.

ABSTRACT

BACKGROUND: In 2010-2017, meningococcal serogroup A conjugate vaccine (MACV) was introduced in 21 African meningitis belt countries. Neisseria meningitidis A epidemics have been eliminated here; however, non-A serogroup epidemics continue. METHODS: We reviewed epidemiological and laboratory World Health Organization data after MACV introduction in 20 countries. Information from the International Coordinating Group documented reactive vaccination. RESULTS: In 2011-2017, 17 outbreaks were reported (31 786 suspected cases from 8 countries, 1-6 outbreaks/year). Outbreaks were of 18-14 542 cases in 113 districts (median 3 districts/outbreak). The most affected countries were Nigeria (17 375 cases) and Niger (9343 cases). Cumulative average attack rates per outbreak were 37-203 cases/100 000 population (median 112). Serogroup C accounted for 11 outbreaks and W for 6. The median proportion of laboratory confirmed cases was 20%. Reactive vaccination was conducted during 14 outbreaks (5.7 million people vaccinated, median response time 36 days). CONCLUSION: Outbreaks due to non-A serogroup meningococci continue to be a significant burden in this region. Until an affordable multivalent conjugate vaccine becomes available, the need for timely reactive vaccination and an emergency vaccine stockpile remains high. Countries must continue to strengthen detection, confirmation, and timeliness of outbreak control measures.