From Agadez to Zinder: estimating coverage of the MenAfriVac™ conjugate vaccine against meningococcal serogroup A in Niger, September 2010 - January 2012.

MenAfriVac™ is a conjugate vaccine against meningitis A specifically designed for Africa. In Niger, the MenAfriVac™ vaccination campaign was conducted in people aged 1-29 years in three phases. The third phase was conducted in November/December 2011 targeting more than 7 million people. We estimated vaccination coverage for the third phase; classified the 31 target districts according to vaccination coverage levels; analysed the factors associated with being vaccinated; described the reasons for non-vaccination; and estimated coverage of the MenAfriVac™ introduction in Niger by aggregating data from all three phases. We classified the districts by clustered lot quality assurance sampling according to a 75% lower threshold and a 90% upper threshold. We estimated coverage using a minimum cluster-sample of 30 x 10 in each region. Two criteria were used to document vaccination status: presentation of vaccination card only or by card and/or verbal history of vaccination (card+history). We surveyed 2390 persons. After the third phase, estimated coverage was 68.8% (95% CI 64.9-72.8) by card only and 90.9% (95% CI 88.6-93.2) by card+history. Five districts were accepted for coverage above 75% based on card only, whereas 25 were accepted based on card+history. Factors positively associated with being vaccinated were younger age (<15 years), female sex, residing in the same household for more than three months, and being informed about the vaccination campaign. The main reason for non-vaccination was not being at home during the campaign. Overall coverage for MenAfriVac™ introduction via 3 phases was 76.1% (95% CI: 72.5-79.6) by card only and 91.9% (95%CI: 89.7-94.1) by card+history.Although estimated coverage was high, pockets of non-vaccination probably still exist in the country; thus, the implementation of mop-up campaigns should be considered. Priorities for the future should include incorporating meningitis A vaccination into the existing immunization schedule and assessing its impact at a population level.