In August 2020, Nigeria achieved a monumental public health milestone by being declared free of wild poliovirus (WPV) by the World Health Organization (WHO). This declaration marked the culmination of decades of concerted efforts involving the Nigerian government, international partners, health workers, and communities. However, the journey did not end there. The WHO’s post-certification audit, initiated in 2025, serves as a critical mechanism to ensure that Nigeria maintains its polio-free status and continues to uphold the highest standards of surveillance, immunization, and outbreak response.
This article delves into the significance of the post-certification audit, the current polio situation in Nigeria, the roles of various stakeholders, and the broader implications for the African region and the global community.
Understanding the Post-Certification Audit
The post-certification audit is a comprehensive evaluation conducted by the WHO to assess a country’s capacity to sustain its polio-free status. Unlike the initial certification process, which focuses on the absence of wild poliovirus transmission, the post-certification audit examines the robustness of surveillance systems, immunization coverage, laboratory containment, and outbreak preparedness.
Key components of the audit include:
- Surveillance Systems: Evaluating the sensitivity and responsiveness of acute flaccid paralysis (AFP) surveillance and environmental monitoring to detect any potential poliovirus transmission.
- Immunization Coverage: Assessing the maintenance of high immunization coverage to prevent the resurgence of poliovirus.
- Laboratory Containment: Ensuring that all poliovirus stocks are securely contained in accredited laboratories to prevent accidental release.
- Outbreak Preparedness: Reviewing the country’s capacity to rapidly respond to any potential poliovirus outbreaks.
The audit process involves documentation reviews, field visits, data analysis, and stakeholder engagement to provide a comprehensive assessment of the country’s polio-free status.
WHO’s Post-Certification Audit Process
The WHO employs a meticulous post-certification audit process to ensure that countries maintain their polio-free status after certification. This process is vital for preventing the resurgence of poliovirus and for sustaining the gains achieved through years of intensive eradication efforts.
Audit Criteria and Standards
WHO’s post-certification audits are guided by stringent criteria that encompass several key areas:
- Surveillance Systems: Countries must maintain high-quality surveillance systems capable of detecting any signs of poliovirus transmission. This includes monitoring for acute flaccid paralysis (AFP) and environmental sampling.
- Immunization Coverage: Sustaining high immunization coverage is crucial to maintain herd immunity and prevent the spread of poliovirus.
- Laboratory Containment: Ensuring that all poliovirus stocks are securely contained in accredited laboratories to prevent accidental release.
- Outbreak Preparedness and Response: Developing and implementing plans to rapidly respond to any potential poliovirus outbreaks.
- National Certification Committees (NCCs): Countries are required to have functional NCCs that oversee and validate polio surveillance and immunization activities.
These criteria are designed to provide a comprehensive assessment of a country’s capacity to prevent and respond to any potential poliovirus transmission.
Methodology of the Audit
The post-certification audit process involves several key steps:
- Documentation Review: Countries submit detailed reports outlining their surveillance systems, immunization coverage, laboratory containment measures, and outbreak preparedness plans. These reports are reviewed by WHO and independent experts.
- Field Verification Visits: WHO conducts field visits to verify the information provided in the documentation. These visits include interviews with health officials, observations of surveillance activities, and assessments of laboratory facilities.
- Data Analysis: Collected data is analyzed to assess the effectiveness and reliability of surveillance systems, the adequacy of immunization coverage, and the robustness of outbreak response plans.
- Stakeholder Engagement: Engaging with local communities, health workers, and other stakeholders to understand the practical challenges and successes in maintaining polio-free status.
- Reporting and Recommendations: Based on the findings, WHO provides feedback and recommendations to the country to address any identified gaps or weaknesses.
This rigorous methodology ensures that the audit process is thorough and that countries are held accountable for maintaining their polio-free status.
Timeline and Expected Outcomes
The timeline for the post-certification audit process varies depending on the country’s specific circumstances. However, the general process includes:
- Initial Assessment: Conducted within the first year following certification to identify any immediate issues.
- Follow-up Audits: Regular audits every 1-2 years to monitor ongoing compliance with WHO’s criteria.
- Final Evaluation: A comprehensive evaluation after 5 years to assess the long-term sustainability of polio-free status.
The expected outcomes of the audit process include:
- Identification of Strengths and Weaknesses: Highlighting areas where the country is performing well and areas that require improvement.
- Actionable Recommendations: Providing clear, actionable recommendations to address identified gaps.
- Sustained Polio-Free Status: Ensuring that the country maintains its polio-free status through continuous improvement and vigilance.
By adhering to this structured audit process, WHO aims to support countries in their efforts to sustain polio-free status and contribute to the global goal of eradicating polio worldwide.
Nigeria’s Current Polio Situation
Understanding Nigeria’s current polio landscape is essential to grasp why the WHO’s post-certification audit is both timely and critical. Although Nigeria was certified free of wild poliovirus (WPV) in 2020, the country still faces ongoing challenges, primarily linked to circulating vaccine-derived polioviruses (cVDPVs), especially type 2 (cVDPV2). Let’s break down the facts clearly.
Status of Wild Poliovirus
Nigeria has not reported any case of wild poliovirus since 2016, a significant achievement after decades of intense eradication efforts. This absence was pivotal for the African region’s certification as polio-free. Surveillance data show that the systems in place are capable of detecting poliovirus cases swiftly, reflecting strong disease monitoring and response frameworks.
This achievement means that Nigeria has successfully interrupted the natural transmission of wild poliovirus, a virus known for causing irreversible paralysis and death in children. However, the fight is not over simply because WPV has been eliminated.
Circulating Vaccine-Derived Poliovirus (cVDPV)
Here’s where it gets complex: the oral polio vaccine (OPV) contains a weakened but live virus that, in rare instances, can genetically mutate and circulate in under-immunized communities, causing outbreaks of cVDPV. Nigeria has faced recurrent outbreaks of cVDPV type 2, particularly since the global switch from trivalent OPV to bivalent OPV in 2016.
Between 2018 and 2024, Nigeria experienced multiple cVDPV2 outbreaks concentrated in northern regions where immunization gaps and insecurity complicate vaccination efforts. According to WHO surveillance reports, these outbreaks are not due to failure but rather reflect the continued need for high immunization coverage and rapid response when cases emerge.
Strategies to Address cVDPV
Nigeria has taken robust measures to control cVDPV outbreaks:
- Supplementary Immunization Activities (SIAs): Repeated mass vaccination campaigns targeting children under five have been deployed to raise immunity levels.
- Use of Novel OPV2 (nOPV2): In recent years, Nigeria introduced the novel OPV2 vaccine, designed to be genetically more stable, reducing the risk of vaccine-derived outbreaks.
- Strengthening Routine Immunization: Efforts to improve the overall immunization system have been intensified, including cold chain enhancements and healthcare worker training.
- Enhanced Surveillance: Nigeria has scaled up environmental sampling alongside AFP surveillance to detect poliovirus circulation early.
Challenges in Maintaining Polio-Free Status
Despite progress, several challenges persist:
- Insecurity and Access Issues: Armed conflicts and insurgency in parts of northern Nigeria hinder vaccination teams’ access, creating pockets of under-immunized children.
- Vaccine Hesitancy: Cultural and religious misconceptions about vaccines occasionally hamper immunization efforts.
- Health System Gaps: Variability in healthcare infrastructure between urban and rural areas affects consistent vaccine delivery.
- Surveillance Sensitivity: Maintaining highly sensitive surveillance is resource-intensive and requires ongoing commitment.
Nigeria’s polio landscape is thus a mix of triumph and ongoing vigilance. While the absence of wild poliovirus is a testament to effective eradication efforts, the presence of vaccine-derived strains demands continuous attention. This dual reality underscores why the WHO’s post-certification audit will scrutinize Nigeria’s surveillance systems, immunization programs, and outbreak response capacities. The audit aims to ensure that Nigeria remains polio-free—not just on paper but in practice.
Stakeholder Involvement and Commitment
The journey to a polio-free Nigeria has been a collective effort, involving the unwavering commitment of various stakeholders, each playing a pivotal role in achieving and maintaining this status.
Role of the Nigerian Government
The Nigerian government has been at the forefront of the polio eradication initiative, providing the necessary leadership and resources to combat the disease. Key actions include:
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Policy Development and Implementation: The government formulated and executed national policies aimed at eradicating polio, ensuring that immunization programs were integrated into the broader health system.
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Resource Allocation: Significant financial and human resources were allocated to support vaccination campaigns, surveillance activities, and healthcare infrastructure improvements.
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Coordination and Oversight: Establishing the National Primary Health Care Development Agency (NPHCDA) to oversee polio eradication efforts and coordinate with state and local governments.
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Legislative Support: Enacting laws and regulations that facilitated the smooth implementation of immunization programs and ensured accountability.
International Partners and Organizations
Global organizations and international partners have provided technical expertise, funding, and logistical support throughout the polio eradication process. Notable contributors include:
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World Health Organization (WHO): Provided technical guidance, conducted surveillance, and supported the certification process.
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UNICEF: Assisted in community mobilization, social mobilization campaigns, and the distribution of vaccines.
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Rotary International: Played a crucial role in advocacy, fundraising, and volunteer mobilization.
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Bill & Melinda Gates Foundation: Offered financial support and policy advocacy to sustain eradication efforts.
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Gavi, the Vaccine Alliance: Supported the procurement and distribution of vaccines, ensuring equitable access.
Community Engagement and Awareness
Local communities have been instrumental in the success of polio eradication efforts. Their involvement included:
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Community Health Workers: Trained individuals who conducted door-to-door vaccination campaigns and educated families about the importance of immunization.
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Traditional and Religious Leaders: Played a significant role in dispelling myths and misconceptions about vaccines, thereby increasing acceptance within communities.
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Parents and Caregivers: Their active participation in vaccination campaigns ensured that children received the necessary doses.
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Local Media: Utilized to disseminate information, raise awareness, and encourage participation in immunization activities.
The WHO’s post‑certification audit marks a decisive milestone in Nigeria’s journey to sustain its polio‑free status. This rigorous evaluation not only confirms the robustness of surveillance systems, immunization coverage, laboratory safeguards, and outbreak preparedness—it also reinforces national accountability.
Recent moves by the WHO, UNICEF, and the Global Polio Eradication Initiative, including the accreditation of the Ibadan sequencing laboratory and renewed commitments from traditional leaders, underscore the strategic focus on eliminating all poliovirus types by the end of 2025. These efforts are backed by strengthened primary health care networks and the full integration of polio‑born assets into Nigeria’s wider health system.
Given the persistence of circulating vaccine‑derived poliovirus type 2 in parts of northern Nigeria, the audit serves both as validation and a call to sustained action. It demands continued political leadership, community engagement, high-quality vaccination campaigns, and seamless cross-border coordination.
Ultimately, this audit is more than a review—it is Nigeria’s blueprint for vigilance, resilience, and ownership. By embedding the WHO’s recommendations into national health planning and sustaining momentum from all stakeholders, Nigeria can confidently guard its polio‑free achievements and contribute meaningfully to the global eradication effort.
