Global health leaders are nearing a historic milestone: the eradication of wild poliovirus, a disease that once paralyzed more than 350,000 children annually across 125 countries. Today, the virus remains endemic in just two countries Afghanistan and Pakistan , where persistent pockets of transmission continue to challenge decades of progress.
The current effort underway represents the most coordinated, technically advanced, and politically sensitive eradication campaign in the program’s history. Success would make polio only the second human disease ever eliminated, after smallpox. But the final stage is also the most complex, requiring synchronized operations, intensive surveillance, and sustained community engagement in some of the world’s most difficult environments.
This explainer outlines the key elements of the final eradication push, the challenges that remain, and why the next 12–18 months are critical for global health.
Why Afghanistan and Pakistan Remain the Last Endemic Strongholds
Wild poliovirus now circulates only in select regions of Afghanistan and Pakistan , areas characterized by insecurity, population mobility, and low vaccination coverage.
Pakistan
Pakistan continues to face:
- Vaccine hesitancy and misinformation, often rooted in longstanding distrust of health campaigns.
- Security risks affecting vaccination teams in certain districts.
- High population mobility across provinces and across the border with Afghanistan, enabling the virus to travel quickly.
Despite these barriers, Pakistan has seen dramatic declines in detected cases in recent years, and health officials say interruption of transmission is within reach , if high vaccination coverage can be sustained.
Afghanistan
Decades of conflict have created significant operational barriers:
- Some regions, especially in the east and south, remain inaccessible to vaccination teams.
- Shifts in governing authority have altered community engagement dynamics, requiring new negotiation strategies.
- Political instability limits the ability to maintain consistent surveillance and outreach.
These chronic challenges have made it difficult to reach “zero-dose” children , those who have never received a single vaccine dose , who represent the highest risk group for sustaining transmission.
The Strategic Pillars of the Final Eradication Campaign
The final stage of polio eradication hinges on several coordinated strategies designed to close immunity gaps, strengthen surveillance, and ensure long-term stability.
High-Level Political Commitment
Both Afghanistan and Pakistan have reaffirmed their commitment to polio eradication at the national level, emphasizing coordinated planning between health ministries, provincial authorities, and international partners.
Political endorsement is essential for:
- Securing safe access for health workers
- Supporting vaccination campaigns in high-risk districts
- Maintaining public messaging to counter misinformation
Deployment of the Novel Oral Polio Vaccine Type 2 (nOPV2)
One of the campaign’s most important tools is nOPV2, a genetically stabilized oral vaccine designed to:
- Provide strong intestinal immunity
- Reduce the risk of vaccine-derived poliovirus mutations
- Be safe for use in areas where immunity gaps persist
This vaccine addresses the primary challenge faced in the final phase: the risk of circulating vaccine-derived poliovirus (cVDPV2), which can appear in under-immunized populations.
Reaching “Zero-Dose” Children
The focus on unvaccinated children is critical. These children often live in:
- Remote mountainous villages
- Informal settlements
- Nomadic or semi-nomadic communities
- Areas with high insecurity or restricted access
Reaching them requires:
- Mobile vaccination units
- Local community engagement networks
- Cross-border coordination
- House-to-house strategies led by trusted female vaccinators when culturally appropriate
Children receiving their first dose through these efforts are protected not only individually but also contribute to achieving collective immunity.
A Global Funding Commitment
The campaign is backed by approximately US$4.8 billion over five years from:
- The Bill & Melinda Gates Foundation
- U.S. Centers for Disease Control and Prevention (CDC)
- Major European donors
- Regional government partners
This funding supports:
- Vaccine procurement
- Cold-chain systems
- Field personnel
- Surveillance networks
- Rapid response operations in case of virus detection
According to financial planners, stable funding is essential to maintain campaign momentum and ensure no gaps occur during critical vaccination rounds.
The Cross-Border Challenge: The Greatest Barrier to Eradication
The border between Afghanistan and Pakistan is the epicenter of the global eradication effort. The region functions as a single epidemiological block, meaning neither country can interrupt transmission without parallel progress across the border.
Continuous Population Movement
Nomadic families, seasonal laborers, traders, and displaced populations routinely cross the border. This movement:
- Reinforces immunity gaps
- Allows the virus to reappear even after successful campaigns
- Makes localized outbreaks difficult to contain
The Strategy: Synchronized Vaccination
To prevent reinfection cycles, both countries must:
- Conduct vaccination campaigns on exactly the same days
- Share data on target populations and coverage rates
- Coordinate vaccine deliveries and cold-chain usage
Without synchronization, unvaccinated children crossing the border can quickly undermine progress in either country.
Security and Access Barriers
Some of the world’s most challenging operational environments lie along the frontier region.
Insecurity in Border Districts
Certain districts continue to experience:
- Armed conflict
- Intermittent violence
- Restrictions on movement
These conditions create dangerous working environments for vaccinators and often limit access to full communities.
The Strategy: Transit-Point Vaccination
Vaccination booths at official crossing points such as Torkham and Chaman allow teams to:
- Vaccinate children moving between countries
- Track high-risk families
- Maintain consistent coverage among mobile populations
Even if house-to-house campaigns are not possible in some areas, transit-point vaccination ensures at least intermittent protection.
Negotiating Access Through Local Leaders
In Afghanistan, certain remote areas remain difficult to reach. Health teams work closely with:
- Community elders
- Religious leaders
- Local councils
Negotiated access is a core strategy for reaching children in “inaccessible” zones, especially for all-female vaccination teams, which are often required for cultural reasons.
Surveillance and Data Sharing: The Invisible Backbone of Eradication
Ending polio is impossible without rapid detection of virus circulation.
Environmental Surveillance
Health teams routinely collect and analyze sewage samples from urban areas to detect silent transmission. Positive environmental samples can reveal circulating virus weeks before clinical cases appear.
AFP Surveillance
All suspected cases of Acute Flaccid Paralysis (AFP) in children are investigated immediately, with testing conducted in WHO-accredited laboratories.
The Challenge: Politically Sensitive Data Sharing
Timely information exchange between Afghanistan and Pakistan is essential but can be complicated by:
- Political tensions
- Administrative barriers
- Incompatible data systems
The Strategy: Joint Technical Coordination
WHO and global partners facilitate joint reviews that:
- Map transmission chains
- Identify gaps in immunity
- Trigger synchronized outbreak response campaigns
This cross-border epidemiological synchronization is considered one of the program’s most important achievements.
Why the Next 12–18 Months Are Pivotal
Global health experts agree: this is likely the final window to eradicate wild poliovirus.
Success depends on:
- Maintaining synchronized vaccination rounds
- Reaching zero-dose children in high-risk districts
- Ensuring safe access for health workers
- Rapid detection and response to any virus circulation
- Sustained community engagement and political support
Any significant disruption whether due to conflict, funding shortfalls, or vaccine refusal risks allowing the virus to persist or spread.
The global health community recognizes that eradication is within reach, but victory depends on unwavering operational precision and consistent outreach in the two remaining endemic countries.
0 Comments