Whom and where are we not vaccinating? Coverage after the introduction of a new conjugate vaccine against group A meningococcus in Niger in 2010.

Vaccination coverage surveys - Publication

abstract: MenAfriVac is a new conjugate vaccine against Neisseria

meningitidis serogroup A developed for the African \"meningitis

belt\". In Niger, the first two phases of the MenAfriVac

introduction campaign were conducted targeting 3,135,942

individuals aged 1 to 29 years in the regions of Tillabéri, Niamey,

and Dosso, in September and December 2010. We evaluated the

campaign and determined which sub-populations or areas had low

levels of vaccination coverage in the regions of Tillabéri and

Niamey. After Phase I, conducted in the Filingué district, we

estimated coverage using a 30×15 cluster-sampling survey and nested

lot quality assurance (LQA) analysis in the clustered samples to

identify which subpopulations (defined by age 1-14/15-29 and sex)

had unacceptable vaccination coverage (<70%). After Phase II, we

used Clustered Lot Quality Assurance Sampling (CLQAS) to assess if

any of eight districts in Niamey and Tillabéri had unacceptable

vaccination coverage (<75%) and estimated overall coverage.

Estimated vaccination coverage was 77.4% (95%CI: 84.6-70.2) as

documented by vaccination cards and 85.5% (95% CI: 79.7-91.2)

considering verbal history of vaccination for Phase I; 81.5%

(95%CI: 86.1-77.0) by card and 93.4% (95% CI: 91.0-95.9) by verbal

history for Phase II. Based on vaccination cards, in Filingué, we

identified both the male and female adult (age 15-29)

subpopulations as not reaching 70% coverage; and we identified

three (one in Tillabéri and two in Niamey) out of eight districts

as not reaching 75% coverage confirmed by card. Combined use of LQA

and cluster sampling was useful to estimate vaccination coverage

and to identify pockets with unacceptable levels of coverage (adult

population and three districts). Although overall vaccination

coverage was satisfactory, we recommend continuing vaccination in

the areas or sub-populations with low coverage and reinforcing the

social mobilization of the adult population.