By Simpson Global Media News Desk
Nigeria is strengthening surveillance for polio and other vaccine-preventable diseases after an independent review identified gaps in the country's ability to detect suspected cases quickly, particularly in some secondary and tertiary health facilities and among mobile, migrant and underserved populations.
The review, conducted between August 24 and September 9, covered 13 high-priority states, 39 local government areas and 111 health facilities across Nigeria's six geopolitical zones.
More than 95 per cent of the surveillance network assessed during the exercise performed strongly against the indicators examined, according to the World Health Organisation. However, the review also identified weaknesses that could delay the reporting and investigation of cases in communities that are difficult to reach through routine health services.
The findings have prompted government teams to develop corrective measures that include mapping migrant settlements and pastoral routes, improving population estimates and expanding searches for possible cases in places where conventional surveillance may not reach children.
In conflict-affected areas of northern Nigeria, proposed measures include involving retired health workers in case-finding and immunisation activities. Authorities are also considering the use of satellite imagery to improve estimates of the size and location of remote settlements.
The development comes six years after the African Region was certified free of wild poliovirus. Nigeria achieved that milestone in August 2020, but circulating vaccine-derived poliovirus remains a public-health concern, making continued vaccination and surveillance necessary.
A Case That Illustrates Why Surveillance Matters
The latest WHO report uses the experience of a four-year-old girl in Kano State to illustrate how Nigeria's surveillance system is expected to work.
When the child's mother, Shafa'atu Isyaku, noticed that her daughter could not move one leg, she took her to a primary healthcare centre.
Health workers assessed the child and reported the symptoms through Nigeria's disease-surveillance network.
The report classifies sudden weakness or paralysis in a child's limbs as acute flaccid paralysis, or AFP. AFP has several possible causes and does not automatically mean that a child has polio.
The significance of reporting such symptoms is that health authorities need to investigate quickly to determine whether poliovirus is responsible or whether another medical condition explains the paralysis. In the Kano case, polio was eventually ruled out, and the child was referred for further medical treatment.
The episode demonstrates the distinction between detecting a suspected case and confirming polio.
A child presenting with sudden weakness is not automatically a confirmed polio patient.
Instead, the symptom triggers a surveillance process in which health workers report the case, surveillance officers investigate it and appropriate laboratory and epidemiological procedures are used to determine whether poliovirus is involved.
That process is central to maintaining Nigeria's gains against the disease.
Why Nigeria Still Needs Polio Surveillance
Nigeria's certification as free of wild poliovirus in 2020 was a major milestone in the African Region's polio-eradication effort.
But certification against wild poliovirus does not eliminate the need for surveillance.
WHO says circulating variant poliovirus remains a public-health threat, particularly in communities where vaccination coverage is insufficient.
The distinction is important.
Wild poliovirus and circulating vaccine-derived poliovirus are different epidemiological problems, although both can cause paralysis.
The National Primary Health Care Development Agency says its polio outbreak-response programme focuses on early detection and rapid response to poliovirus transmission. Its surveillance activities include active searches for acute flaccid paralysis cases and environmental sampling.
The agency's explanation of circulating vaccine-derived poliovirus notes that such outbreaks can occur when a weakened vaccine strain circulates for an extended period in populations with insufficient immunity.
In highly immunised communities, the virus has less opportunity to circulate.
Where substantial numbers of children remain unvaccinated or under-immunised, however, transmission can continue and create conditions in which a vaccine-derived strain becomes capable of causing outbreaks.
This is why Nigeria's polio programme continues to combine immunisation with surveillance.
Vaccination reduces susceptibility.
Surveillance provides early warning.
Rapid investigation helps determine whether a suspected case represents poliovirus transmission.
Environmental surveillance can provide another route for detecting virus circulation, including where children with symptoms have not been identified through routine clinical reporting.
What the 2026 Review Examined
The latest surveillance review was conducted over more than two weeks and deliberately extended beyond a narrow assessment of hospitals.
The exercise was led by the National Primary Health Care Development Agency and the National Polio Emergency Operations Centre, with support from WHO and partners in the Global Polio Eradication Initiative.
Teams examined records, visited health facilities, followed up reported cases and held discussions with government officials, healthcare workers, traditional leaders, caregivers and community informants.
The review covered 13 priority states and 39 local government areas, with 111 health facilities included in the assessment.
Importantly, the exercise also examined communities that may be poorly served by conventional health infrastructure.
These included internally displaced people, migrants, nomadic communities, border populations and people living in conflict-affected areas.
That approach reflects a central challenge in disease surveillance: the people most difficult to reach can also be the people most likely to be missed by systems that depend heavily on routine attendance at health facilities.
A child who lives near a functioning primary healthcare centre may have several opportunities to come into contact with health workers.
A child living in a remote settlement, a temporary displacement camp, a nomadic community or an insecure area may have fewer opportunities.
If the child develops symptoms associated with a vaccine-preventable disease, the case may not immediately enter the formal surveillance system.
The review therefore looked beyond the facilities themselves to the populations and communities they are supposed to serve.
Strong Performance, But Important Weaknesses
The overall finding was not that Nigeria's surveillance system had failed.
WHO reported that more than 95 per cent of the network performed strongly across the indicators assessed.
But the remaining gaps matter because disease surveillance is highly dependent on speed.
For diseases such as polio, delayed detection can mean delayed investigation, delayed laboratory confirmation and delayed response.
The review identified critical gaps particularly in secondary and tertiary health facilities and among mobile, migrant and underserved populations.
The findings suggest that strengthening surveillance is not simply a question of adding more facilities.
It also involves making sure that existing facilities recognise suspected cases, report them appropriately and maintain the systems required to transmit information rapidly.
It means establishing ways of finding cases outside formal facilities.
And it requires health authorities to understand where populations are located, including communities whose movements may make conventional population estimates difficult.
The result is a surveillance system that must operate at several levels at once.
Hospitals and clinics provide one layer.
Community health workers and volunteers provide another.
Traditional leaders, caregivers and other community informants can provide additional channels through which suspected cases reach health authorities.
Environmental surveillance can provide another source of information.
The more effectively these components connect, the greater the likelihood that a suspected case will be recognised and investigated quickly.
The Challenge of Mobile Populations
One of the most important findings from the review concerns populations that move from one location to another.
Nigeria has substantial mobile populations, including pastoral communities, migrants, internally displaced people and populations living along or moving across borders.
A surveillance system based entirely on fixed facilities can struggle to follow these populations.
A child may not remain in the same local government area long enough to develop an established relationship with a health facility.
Families may also cross administrative boundaries in search of work, grazing land, security or other necessities.
That movement can complicate efforts to determine how many people live in a particular area and where health services should be deployed.
The review therefore recommends mapping migrant settlements and pastoral routes.
Improving population estimates is another proposed corrective measure.
These steps may appear administrative, but they have direct implications for disease control.
Health authorities need to know where people are before they can determine where to deploy surveillance officers, vaccination teams and other public-health resources.
WHO says government teams are developing corrective measures based on the findings, including expanded case searches in locations where routine health services may miss children.
Conflict Adds Another Layer of Difficulty
The problem becomes more complicated in conflict-affected areas.
Parts of north-eastern and north-western Nigeria have communities where insecurity can disrupt normal healthcare access.
Health facilities may be difficult to reach.
Health workers may not be able to move freely.
Families may relocate repeatedly.
Some communities may be physically accessible only at certain times or through arrangements involving local leaders and security structures.
In such environments, relying exclusively on routine facility-based surveillance creates a risk that suspected cases will remain invisible.
The review therefore proposes additional approaches for affected areas.
One is the engagement of retired health workers in case searches and immunisation activities.
Another is the use of satellite imagery to help estimate the location and population of remote settlements.
Satellite imagery does not replace health workers.
Rather, it can help authorities understand where settlements are located and identify places that may not be fully represented in existing administrative records.
That information can then be used to plan physical surveillance and immunisation activities.
The proposal reflects the increasing role of data and technology in public health.
Where conventional records are incomplete, additional information sources can help health authorities build a more accurate picture of communities that need services.
The Importance of Community Reporting
Formal health facilities are not the only source of surveillance information.
WHO's account of the Kano case highlights the role played by the child's mother in seeking medical attention after noticing an unusual symptom.
The organisation also says community members, traditional leaders and local volunteers can be among the first people to report suspected cases.
That makes community awareness an important part of disease surveillance.
A surveillance system can only investigate a case after somebody recognises a reason to report it.
If a caregiver does not know that sudden weakness or paralysis in a child should be assessed promptly, the health system may not receive the information early enough.
Likewise, a community volunteer or traditional leader who recognises a potential case can provide an additional pathway to health authorities.
The Kano disease-surveillance officer quoted by WHO emphasised the importance of receiving information quickly so that investigations can begin sooner.
The system therefore depends on both technical infrastructure and human relationships.
Data platforms and reporting procedures matter.
So do trust, communication and the willingness of families to bring children to health facilities.
What Acute Flaccid Paralysis Means
Acute flaccid paralysis is a surveillance term rather than a diagnosis of polio.
The word “acute” refers to sudden onset.
“Flaccid” describes weakness or reduced muscle tone.
“Paralysis” refers to loss of movement.
A child displaying such symptoms can have conditions unrelated to poliovirus.
That is why every suspected AFP case requires investigation.
The objective is not to label every child with sudden weakness as having polio.
The objective is to make sure that poliovirus is not missed.
This distinction is especially important in public communication.
A report of a suspected case should not automatically be presented as confirmation of an outbreak.
In the Kano example, the child's symptoms triggered the surveillance response, but polio was ultimately ruled out.
The episode nevertheless served the purpose of the surveillance system.
The child was identified.
The symptoms were reported.
An investigation was conducted.
Polio was excluded.
The child was referred for further treatment.
That sequence demonstrates why surveillance systems remain necessary even when the suspected disease is not confirmed.
Surveillance Beyond the Hospital
Nigeria's national polio programme uses more than one method to look for evidence of transmission.
NPHCDA identifies acute flaccid paralysis case searches and environmental sampling as key surveillance activities.
Environmental surveillance is particularly useful because poliovirus can circulate without producing an obvious cluster of paralysis cases.
Sampling sewage and other environmental sites can provide information about virus circulation in a community.
The wider polio programme also includes supplementary immunisation activities and targeted responses designed to address immunity gaps.
NPHCDA's programme includes approaches such as National Immunisation Plus Days, sub-national immunisation days and targeted local responses. It also lists initiatives intended to reach chronically missed children and communities that are difficult to access because of geography or insecurity.
The existence of these different approaches illustrates why polio eradication is not simply a vaccination exercise.
It is a surveillance, immunisation, logistics, community-engagement and emergency-response operation.
Each component addresses a different point in the transmission chain.
Vaccination Remains the Core Protection
Surveillance can identify risk, but it does not itself prevent infection.
Vaccination remains the primary tool for protecting children from poliovirus.
NPHCDA states that the best protection is achieved when children receive recommended polio vaccines through routine immunisation and supplementary campaigns, alongside strong disease surveillance.
Repeated doses are part of the immunisation strategy because multiple doses are needed to build and maintain adequate protection.
This is particularly important in areas where routine immunisation coverage has been disrupted or where large numbers of children have historically been missed.
A surveillance system can tell authorities where problems may be emerging.
Vaccination campaigns then provide an opportunity to close immunity gaps.
The two activities therefore reinforce each other.
Surveillance identifies where and how to look.
Immunisation reduces the population's vulnerability to the virus.
The Difference Between Wild and Vaccine-Derived Poliovirus
Nigeria's 2020 certification concerned wild poliovirus.
That achievement remains important, but it does not mean that every form of poliovirus has disappeared from the country.
NPHCDA explains that circulating vaccine-derived poliovirus can emerge where a weakened vaccine strain continues to circulate for a prolonged period among populations with inadequate immunity.
The agency's current polio information states that Nigeria remains affected by circulating vaccine-derived poliovirus outbreaks despite the earlier certification against wild poliovirus.
The distinction is sometimes confusing to the public.
The phrase “vaccine-derived” can give the impression that vaccination itself is producing a conventional outbreak.
The epidemiological process is more specific.
The oral polio vaccine contains weakened virus.
When vaccination coverage is high, sustained transmission is unlikely because most children are protected.
When immunity is low, however, the weakened strain can circulate for an extended period.
In rare circumstances, continued circulation can allow genetic changes that enable the virus to regain the ability to cause paralysis and produce an outbreak.
The practical implication for public health is that low immunisation coverage creates a vulnerability.
That is why vaccination remains necessary even after wild poliovirus has been eliminated from a country.
Why Surveillance Must Continue After Certification
Disease elimination programmes face a recurring challenge after major milestones are reached.
Once a disease becomes less visible, communities and health systems may become less alert to it.
But infectious diseases can exploit gaps in immunity and surveillance.
Nigeria's 2020 certification therefore marked a major achievement, not the end of the surveillance effort.
WHO's latest report explicitly stresses the need for continued vigilance because circulating variant poliovirus remains a threat.
The organisation's position is that maintaining progress requires surveillance capable of detecting threats early and directing rapid response.
This principle extends beyond polio.
A functioning disease-surveillance system can also provide infrastructure for detecting other vaccine-preventable diseases and public-health threats.
The latest review was therefore conducted not only for polio but for polio and other vaccine-preventable diseases.
The surveillance infrastructure developed through the eradication programme can support broader public-health preparedness.
The Gender Findings
The review also examined the gender distribution of acute flaccid paralysis cases assessed during the exercise.
WHO reported that 45 per cent of reviewed AFP cases were female and 55 per cent were male.
The figures are descriptive rather than evidence by themselves of a meaningful difference in disease risk.
They show how the reviewed cases were distributed by sex, but they do not establish why the distribution occurred or whether it reflects differences in exposure, healthcare-seeking behaviour, population structure or other factors.
The more immediate significance of the review lies in its assessment of the surveillance system itself.
The objective was to determine whether suspected cases can be found, reported and investigated promptly.
Integrating Surveillance With Primary Healthcare
The review is also linked to Nigeria's broader efforts to strengthen primary healthcare.
The National Primary Health Care Development Agency has responsibility for developing and supporting primary healthcare services across the country, while its disease-control and immunisation structure includes routine immunisation, outbreak response and surveillance functions.
This means the polio surveillance system does not operate separately from the country's wider primary-healthcare infrastructure.
A primary healthcare centre may be the first point of contact for a child with a concerning symptom.
The quality of the interaction at that level can determine whether the case enters the surveillance system promptly.
If frontline workers recognise the symptom, report it and initiate the appropriate investigation, the system works as intended.
If the facility lacks awareness, staff or reporting capacity, the case may be delayed.
Strengthening surveillance therefore also means strengthening the health facilities and workers who serve as the first line of detection.
Connecting the Findings to National Health Planning
WHO says the review will support implementation of Nigeria's National Polio Emergency Action Plan.
It also contributes to the Nigeria Health Sector Renewal Investment Initiative, which brings together government and partners around national health priorities including stronger primary healthcare and disease preparedness.
The findings will also support implementation of Nigeria's Integrated Disease Surveillance and Response framework.
That framework provides a broader structure for detecting and responding to public-health threats.
The International Health Regulations provide an additional international framework for countries to detect, assess, report and respond to public-health risks.
Polio surveillance therefore sits within a much larger health-security system.
The same principles — early detection, rapid information sharing, investigation and response — are applicable to a range of infectious-disease threats.
What Happens Next
The immediate task is to translate the review findings into operational changes.
WHO says government teams are already developing corrective measures.
Among the proposed actions are mapping migrant settlements, mapping pastoral routes, improving population estimates and expanding case searches in places where routine services may miss children.
Conflict-affected areas are expected to receive specific attention.
The proposed use of retired health workers could expand the pool of people available for case searches and immunisation activities.
Satellite imagery could provide additional information for locating remote settlements.
These measures will need to be connected to the existing reporting and response system.
Finding a suspected case is only the first step.
The information must reach surveillance officers.
The case must be investigated.
Samples may need to be collected and analysed.
Authorities must determine whether there is evidence of poliovirus transmission.
If virus circulation is detected, vaccination and other response measures may need to be intensified.
The effectiveness of the system ultimately depends on how quickly these stages connect.
The Human Element
Behind the statistics about states, local government areas and health facilities are individual families.
The story of the Kano child illustrates why surveillance indicators have practical consequences.
A caregiver noticed that something was wrong.
A health facility responded.
The suspected case was reported.
Surveillance officers investigated.
Polio was ruled out.
The child was referred for additional care.
That process is the human face of a system that can otherwise appear as a series of numbers on a monitoring dashboard.
For families, the value of surveillance is not simply that government can produce reports.
Its value is that a child displaying a potentially serious symptom is seen, assessed and connected to the appropriate response.
WHO quoted the child's mother as saying that when a child is unwell, families want someone to listen and act quickly.
That expectation is central to public-health surveillance.
The Role of Health Workers
Frontline health workers remain critical to the success of the system.
They are often the first professionals to see a child with sudden weakness.
They must recognise that the symptom requires investigation even when the final diagnosis may have nothing to do with polio.
They also need functioning channels through which information can reach surveillance authorities.
For health workers in remote communities, that can be particularly difficult.
Connectivity may be limited.
Transport may be unreliable.
Security conditions can restrict movement.
Staff shortages can increase workloads.
The review's identification of gaps in secondary and tertiary facilities and underserved populations suggests that strengthening the system will require attention to these operational realities.
The objective is not merely to create additional rules.
It is to make the rules workable for people operating in very different environments.
Community Leaders as Part of the Surveillance Chain
The review's inclusion of traditional leaders, community informants and caregivers also reflects the importance of local networks.
In communities where formal health services are not immediately accessible, traditional leaders and local volunteers may know about a child's illness before a health official does.
Their ability to alert health authorities can reduce the delay between the appearance of symptoms and investigation.
That makes community engagement a practical surveillance tool.
It also requires trust.
Families must be willing to report symptoms.
Community representatives must know which symptoms matter.
Health authorities must respond when information is provided.
If any of those links breaks down, the surveillance chain becomes weaker.
WHO's report therefore connects technical surveillance with community engagement and communication rather than treating them as separate activities.
Maintaining Public Confidence
Polio elimination has also demonstrated the importance of public confidence in vaccination.
Nigeria's polio programme has for
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