Impact of the Meningococcal A Conjugate Vaccine Introduction in the African Meningitis Belt, 2010-2017

摘要

Meningococcal meningitis remains a burden in the African meningitis belt. Before 2010, Neisseria meningitidis serogroup A (N. meningitidis A) was the predominant pathogen causing deathly epidemics. The meningococcal A conjugate vaccine (MACV, MenAfrivac) protects against N. meningitidis A. It was introduced in 2010 into highest meningitis risk health districts. There was limited data on the effects of MACV, mainly on the degree of relationship between N. meningitidis A and the MACV immunization coverage. The purpose of this quantitative study was to assess the effectiveness of MACV from 2010 to 2017 in 21 out of 26 countries of the African meningitis belt. An interrupted time series design and nonprobability sampling were used. Secondary data issued from meningitis enhanced surveillance were retrieved from World Health Organization database. The social ecological model was used as a theoretical framework for this study. The binomial negative regression and Pearson's Chi-Square tests were used. The study found that after the MACV introduction there were a high degree of relationship between N. meningitidis A and MACV immunization coverage (χ~2 (1) = 11039.49, p = 0.000, Phi = 0.657, P=0.000), 99% decline of the risk of N. meningitidis A (RR 0.01, 95% CI 0.08-0.013), and 99.6% decline of risk of epidemic due to N. meningitidis A (RR 0.004, 95% CI 0.001-0.016). The study demonstrated that high MACV coverage and high-quality meningitis surveillance were pivotal to reduce the burden of meningococcal meningitis A epidemic in African meningitis belt. Based on the results of this study, it is recommended to development and manufacture an affordable multivalent polysaccharide conjugate vaccine against N. meningitis (A, C, W135, X, Y) and introduce in meningitis belt countries to eliminate meningococcal meningitis in Africa, to update the risk assessment of the meningitis status of Africa meningitis belt after the introduction of MenAfriVac, to continue to improve meningitis enhanced surveillance, and improving public health policies on immunization and meningitis enhanced surveillance to ensure sustainable high immunization coverage of meningococcal vaccines and high quality of meningitis epidemic detection.