Integrating acute flaccid paralysis surveillance, environmental surveillance and vaccination strategies to prevent poliovirus re-emergence in Nigeria: a narrative review

Although wild poliovirus (WPV) transmission has been interrupted in Nigeria, the post-certification era continues to present significant risks of poliovirus re-emergence, driven predominantly by circulating vaccine-derived poliovirus type 2 (cVDPV2). Recurrent detections in multiple countries, including Nigeria—particularly in Zamfara and Kano states between 2022 and 2024 highlight immunity gaps following oral polio virus(OPV2) withdrawal. Expanded surveillance systems, and the introduction of new vaccines such as novel OPV2 (nOPV2) necessitate a coordinated national approach. This narrative review synthesised evidence from materials produced by the World Health Organization (WHO), Global Polio Eradication Initiative (GPEI), United Nations Children’s Fund (UNICEF), United States Centers for Disease Control and Prevention (CDC), and peer-reviewed literature published between 2016 and 2025. Nigeria has expanded environmental surveillance to more than 140 wastewater sites, including Abuja, Lagos, and high-risk zones in Kano, improving early detection of silent poliovirus circulation. Persistent cVDPV2 detection in Zamfara and Kano states demonstrates the continued vulnerability associated with immunity gaps. The introduction of nOPV2—now WHO-prequalified (2023/2024)—offers enhanced genetic stability and reduced reversion risk compared with monovalent OPV2, making it the preferred option for outbreak response. Based on the SAGE guidelines, while nOPV2 is exclusively for outbreak response against cVDPV2, the latter two vaccines are for routine immunization. Neither surveillance mechanisms, nor vaccination alone is sufficient to prevent poliovirus re-emergence. However inspite of the innovations, global IPV coverage gaps (2024 WHO map) continue to pose a risk, especially in low-resource settings.