Polio eradication in Africa: overcoming the final hurdles

¹Ministry of Health, National Public Health Agency, Freetown, Sierra Leone, ²Research and Scientific Division, Sustainable Health Systems, Freetown, Sierra Leone, ³Department of Internal Medicine, University of Port Harcourt Teaching Hospital, Port Harcourt, Nigeria, ⁴Department of Social and Behavioral Science, School of Public Health, University of Ghana, Legon, Ghana, ⁵Scientific Research Unit, Federal Medical Centre, Keffi, Nigeria, ⁶College of Medicine, University of Nigeria, Enugu, Nigeria, ⁷Medix Frontiers, University of Nigeria Enugu Campus, Enugu Nigeria

^&Corresponding author
Alpha Umaru Bai-Sesay, Research and Scientific Division, Sustainable Health Systems, Freetown, Sierra Leone

Perspectives    

Polio and the 50-year legacy of the expanded programme on immunization

The Expanded Programme on Immunization (EPI), launched in 1974, remains one of the most transformative global health initiatives, credited with averting millions of childhood deaths across Africa. Within this legacy, polio eradication stands out as both a triumph and an unfinished mission [1]. From over 350,000 cases of wild poliovirus (WPV) globally in 1988, incidence has fallen by more than 99%, and in August 2020 Africa was certified WPV-free [2]. This milestone represented decades of continental solidarity, mass campaigns, and political commitment. Yet, as the EPI commemorates its 50^th anniversary, outbreaks of circulating vaccine-derived poliovirus type 2 (cVDPV2) have emerged as the Achilles' heel of eradication efforts [3]. These outbreaks expose structural weaknesses that persist within immunization systems: reliance on vertical campaigns, subnational inequities in coverage, and vulnerability to shocks such as conflict and pandemics. Positioning polio eradication within the EPI@50 framework transforms its significance. It is no longer only a vertical, single-disease initiative; it is a stress test for the durability of routine immunization and a preview of the challenges other vaccine-preventable diseases (VPDs) face under systemic strain. Lessons from Polio's successes and setbacks, microplanning innovations, cross-border coordination, and community-led engagement offer a blueprint for how the EPI can evolve into a more resilient, equity-centered platform for the next 50 years.

Burden of cVDPV2 in a changing landscape

Five years after Africa was certified free of wild poliovirus (WPV), the continent remains challenged by outbreaks of circulating vaccine-derived poliovirus type. By mid-2025, over 20 African countries have reported confirmed cases, with Nigeria, Ethiopia, Chad, Niger, and the Democratic Republic of the Congo among the most affected [4] (Table 1). In 2024 alone, Nigeria recorded nearly one-third of the global cVDPV2 burden, highlighting its role as a persistent epicenter of transmission. These outbreaks are not evenly distributed; rather, they reflect stark subnational disparities, where some provinces achieve coverage above 90% while others fall below 50%. Such inequities create fertile ground for sustained transmission [5]. The burden of cVDPV2 extends beyond polio. It is a proxy indicator of the broader fragility of immunization systems. The same conditions that allow cVDPV2 to spread: low coverage, delayed outbreak detection, and community mistrust, have fueled resurgences of measles, cholera, and yellow fever in recent years [6]. The COVID-19 pandemic compounded this burden: WHO estimates that 25 million children missed their first measles dose in 2020, reflecting how systemic shocks disrupt services across all antigens [7]. This creates a vicious cycle, known as the Epidemic-Immunisation Fragility Loop, whereby health crises disrupt routine vaccination, thereby increasing susceptibility to future outbreaks (Figure 1). Epidemic-Immunisation Fragility Loop. This conceptual model illustrates how health crises (such as epidemics, conflict, or climate shocks) disrupt routine immunization services, leading to immunity gaps and increased susceptibility to outbreaks. These outbreaks, in turn, further strain fragile health systems, creating a reinforcing cycle of vulnerability. The framework emphasizes the need for integrated, resilient, and equity-focused immunization systems to break this loop and sustain long-term protection against vaccine-preventable diseases. In this sense, cVDPV2 is more than a polio problem; it is a warning signal that the EPI's unfinished agenda lies in closing equity gaps and ensuring continuity of services in the face of multiple, overlapping crises.

Drivers of ongoing transmission: shared weaknesses across EPI

The persistence of cVDPV2 across Africa reflects structural vulnerabilities that also undermine the Expanded Programme on Immunization more broadly. First, low routine immunization coverage remains the central driver. Despite decades of progress, many countries still fall short of the 90% threshold needed to achieve herd immunity, with some districts reporting coverage below 50%. Weak cold chain infrastructure, shortages of trained health workers, and inadequate microplanning in peri-urban and rural areas perpetuate these gaps [8]. Second, insecurity and mobility continue to compromise access. Conflict in the Lake Chad Basin and the Horn of Africa has left millions of children beyond the reach of vaccination teams, while displacement due to conflict or climate shocks facilitates cross-border spread through porous frontiers [9]. These same dynamics have allowed other vaccine-preventable diseases, such as measles and cholera, to rebound after periods of progress. Third, surveillance gaps undermine timely outbreak detection. Acute flaccid paralysis and environmental surveillance remain concentrated in urban centers, leaving remote and insecure districts under-covered [10]. This mirrors weaknesses seen in yellow fever and cholera control, where delayed detection has fueled regional spread. Lastly, hesitancy, misinformation, and competing health priorities, aggravated by the COVID-19 pandemic, reduce community uptake and political prioritization [11]. Together, these drivers reveal that cVDPV2 is not an anomaly but a symptom of systemic weaknesses that, if unaddressed, threaten the resilience of the EPI's next fifty years.

Innovations and lessons for the future of the EPI

Despite persistent challenges, polio eradication has catalyzed innovations that can be harnessed to strengthen the Expanded Programme on Immunization across Africa. The novel oral polio vaccine type 2 exemplifies rapid, science-driven adaptation. Administered in more than one billion doses globally, over 80% in Africa nOPV2 demonstrates greater genetic stability than earlier formulations, reducing the risk of reversion [12]. Its emergency rollout and WHO prequalification illustrate how Africa can act as a proving ground for safe, accelerated vaccine deployment. Lessons from nOPV2 scale-up can inform future introductions of vaccines for measles, Ebola, malaria, and emerging pathogens. Technological innovation is also reshaping surveillance. AI-based forecasting models, GIS-enabled microplanning, and real-time genomic sequencing are being deployed to track poliovirus spread and identify immunity gaps with unprecedented precision [13]. These tools offer a model for proactive outbreak prevention across all vaccine-preventable diseases. Equally transformative are community-led approaches. Engaging trusted leaders, female vaccinators, and polio survivor networks has helped overcome hesitancy and campaign fatigue. Extending such strategies to measles, HPV, and other vaccines could accelerate uptake [14]. Finally, equity-driven outreach from vaccination at markets and transit hubs to integrated child health services offers a scalable blueprint for reaching zero-dose children. Together, these innovations signal how the polio endgame can generate an “EPI systems dividend,” strengthening routine and emergency immunization for decades to come (Table 2).

Reframing polio eradication as a platform for resilient immunization

Polio eradication is no longer only about interrupting transmission of a single pathogen; it is a lens through which the resilience of Africa's immunization systems can be evaluated. As the Expanded Programme on Immunization marks 50 years, the continent's struggle with circulating vaccine-derived poliovirus type 2 offers lessons that extend far beyond polio. The recurring outbreaks reveal how fragile immunization gains can be when systems are disrupted by epidemics, conflict, or climate shocks [15]. They also highlight the urgent need to shift from vertical, campaign-driven approaches toward integrated, equity-focused systems that can sustain coverage through crises. Three priorities are central to this reframing. First, integration: polio campaigns should deliver multiple antigens, reinforce the routine platform and advance universal health coverage goals. Second, resilience: contingency planning must ensure vaccine delivery continues during epidemics and disasters, supported by pathogen-agnostic surveillance and flexible funding. Third, equity: reaching zero-dose and under-immunized children must remain the cornerstone of both polio and EPI programming. If pursued systematically, these shifts will allow Africa not only to finish the polio endgame but also to embed eradication innovations into the DNA of routine immunization. In doing so, polio becomes more than a victory over one disease, it becomes the foundation for a more resilient, inclusive EPI in its next half-century.

A unified call to action

Africa stands at a crossroads. The certification of wild poliovirus elimination in 2020 remains one of the continent's greatest public health victories, yet the persistence of circulating vaccine-derived poliovirus type highlights that the eradication journey is not complete. As the Expanded Programme on Immunization turns 50, polio is no longer just a disease to be eliminated, it is a mirror reflecting the strengths and weaknesses of Africa's immunization systems. The lessons of the polio endgame must now be translated into a continent-wide commitment to resilient, equity-driven immunization for all vaccine-preventable diseases. This moment demands collective action across three fronts. Governments must embed polio innovations digital surveillance, equity-focused outreach, and integrated campaigns into national immunization strategies and universal health coverage plans. Partners and donors must sustain financing beyond eradication, ensuring that funding mechanisms strengthen routine immunization, not just emergency response. Communities must be engaged as co-owners of eradication, with trusted leaders, women vaccinators, and survivor networks at the center of demand creation and service delivery (Table 3). The unified call is clear: finish polio and use it to build the next generation of immunization systems. Through seizing this opportunity, Africa can both deliver on its promise of a polio-free future and secure the broader vision of an EPI that is resilient, inclusive, and prepared for the next fifty years.

Competing interests     

The author declares no competing interests.

Authors' contributions     

Alpha Umaru Bai-Sesay conceptualized the manuscript, led the writing, and coordinated revisions. Alpha Umaru Bai-Sesay, Chizaram Anselm Onyeaghala, Mark Anum Nortey, Abdullahi Hassan and Ebuka Louis Anyamene made substantial intellectual contributions to the development of key arguments, reviewed and revised multiple manuscript drafts, and approved the final version for submission.

Acknowledgments     

We thank the Global Polio Eradication Initiative and the WHO African Region for providing publicly available data that informs this perspective.

Tables and figure     

Table 1: reported cVDPV2 burden in Africa, 2024-2025 (selected high-burden countries)

Table 2: from polio endgame to EPI@50 resilience: key innovations and system-wide dividends

Table 3: proposed solutions, stakeholders, and levels of implementation for Africa's polio endgame and EPI@50 resilience

Figure 1: epidemic-immunisation fragility loop

References