Routine Vaccination Coverage in Northern Nigeria: Results from 40 District-Level Cluster Surveys, 2014-2015

<div><p>Background</p><p>Despite recent success towards controlling poliovirus transmission, Nigeria has struggled to achieve uniformly high routine vaccination coverage. A lack of reliable vaccination coverage data at the operational level makes it challenging to target program improvement. To reliably estimate vaccination coverage, we conducted district-level vaccine coverage surveys using a pre-existing infrastructure of polio technical staff in northern Nigeria.</p><p>Methods</p><p>Household-level cluster surveys were conducted in 40 polio high risk districts of Nigeria during 2014–2015. Global positioning system technology and intensive supervision by a pool of qualified technical staff were used to ensure high survey quality. Vaccination status of children aged 12–23 months was documented based on vaccination card or caretaker’s recall. District-level coverage estimates were calculated using survey methods.</p><p>Results</p><p>Data from 7,815 children across 40 districts were analyzed. District-level coverage with the third dose of diphtheria-pertussis-tetanus vaccine (DPT3) ranged widely from 1–63%, with all districts having DPT3 coverage below the target of 80%. Median coverage across all districts for each of eight vaccine doses (1 Bacille Calmette-Guérin dose, 3 DPT doses, 3 oral poliovirus vaccine doses, and 1 measles vaccine dose) was <50%. DPT3 coverage by survey was substantially lower (range: 28%–139%) than the 2013 administrative coverage reported among children aged <12 months. Common reported reasons for non-vaccination included lack of knowledge about vaccines and vaccination services (50%) and factors related to access to routine immunization services (15%).</p><p>Conclusions</p><p>Survey results highlighted vaccine coverage gaps that were systematically underestimated by administrative reporting across 40 polio high risk districts in northern Nigeria. Given the limitations of administrative coverage data, our approach to conducting quality district-level coverage surveys and providing data to assess and remediate issues contributing to poor vaccination coverage could serve as an example in countries with sub-optimal vaccination coverage, similar to Nigeria.</p></div

Box-and-whisker plots of routine immunization coverage by vaccination card and recall, across 40 local government areas (LGAs)–Northern Nigeria, 2014–2015.

<p>Estimates of vaccine coverage do not include OPV or measles doses given during supplemental immunization activities. Complete vaccination coverage is defined as receiving eight antigens [Bacille Calmette-Guérin (BCG), Oral Poliovirus (OPV) 1/2/3, Diphtheria-pertussis-tetanus (DPT) 1/2/3, and measles). For boxplot interpretation: the dark line is the median; “hinges” are the top and bottom of the box. The upper and lower "hinges" correspond to the first and third quartiles (25^th and 75^th percentiles). The upper and lower whiskers represent +/- 1.5 * IQR, where IQR is the inter-quartile range, or distance between the first and third quartiles. Data beyond the end of the whiskers are outliers and plotted as points (as specified by Tukey).</p

Coverage estimates with third dose of diphtheria-pertussis-tetanus vaccine (DPT3) across 40 local government areas (LGAs), by state–Northern Nigeria, 2014–2015.

<p>LGAs are grouped by state to illustrate variability in coverage across LGAs within the same state. This data is not representative of state-level coverage since LGAs were purposefully selected. Black vertical lines depict 95% confidence intervals. For comparison, administrative coverage for each LGA (source: World Health Organization, Nigeria; DVD-MT data, 2013) is represented with a black dot.</p

Reported access to routine immunization (RI) services and reasons for non-vaccination, across 40 local government areas (LGAs)–Northern Nigeria, 2014–2015.

<p>Reported access to routine immunization (RI) services and reasons for non-vaccination, across 40 local government areas (LGAs)–Northern Nigeria, 2014–2015.</p

Source and type of information about routine immunization services, across 40 local government areas (LGAs)–Northern Nigeria, 2014–2015.

<p>Source and type of information about routine immunization services, across 40 local government areas (LGAs)–Northern Nigeria, 2014–2015.</p

Administrative coverage estimates vs coverage survey estimates for third dose of diphtheria-pertussis-tetanus vaccine (DPT3).

<p>Administrative coverage estimates vs coverage survey estimates for third dose of diphtheria-pertussis-tetanus vaccine (DPT3).</p