Bridging Surveillance Gaps in Nigeria's Polio Programme: Policy Lessons from the April 2025 National Immunization Plus Days

Although Nigeria was certified free of indigenous wild poliovirus in 2020, recurrent outbreaks of circulating vaccine-derived poliovirus type 2 continue to expose operational weaknesses in surveillance sensitivity, campaign implementation, and subnational outbreak preparedness. This policy analysis examined acute flaccid paralysis surveillance performance during the April 2025 National Immunization Plus Days in Nigeria by synthesizing routinely collected programme monitoring data, geo-verification outputs, Lot Quality Assurance Sampling results, operational implementation reports, and national AFP surveillance indicators. The analysis showed that national surveillance indicators exceeded recommended thresholds, with a non-polio AFP rate of 11.9, stool adequacy of 99%, and non-polio enterovirus detection rate of 12.1%. However, programme-level evidence revealed important implementation gaps. Only 71% of targeted settlements had documented geo-verification, leaving nearly one-third without verifiable evidence of field reach, while 88% of Local Government Areas met the ≥90% LQAS campaign-quality threshold. Operational reports further identified weaknesses in supervision, logistics, data quality, reporting timeliness, community engagement, and feedback systems. The reduction in states reporting poliovirus detections from 15 to 9 was interpreted cautiously as a signal requiring further investigation rather than definitive evidence of reduced transmission. The findings demonstrate that favourable national surveillance indicators may coexist with localized geographic and operational gaps that can weaken early detection and outbreak response. Strengthening Nigeria’s polio surveillance system therefore requires geo-enabled monitoring, independent validation of campaign performance, community-based case detection, data-quality assurance, supervisory accountability, and integrated digital reporting systems. These reforms are essential for sustaining Nigeria’s polio-free status, improving detection of vaccine-derived poliovirus transmission, and reinforcing broader public health emergency preparedness.