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

Vaccination coverage surveys - Publication

abstract: 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.