By Michael Gwarisa
Even though the world has made remarkable progress in the fight against polio, with wild poliovirus now circulating in only two countries, Afghanistan and Pakistan, a new challenge has emerged: vaccine-derived poliovirus (VDPV), which is causing outbreaks in previously polio-free regions.
The development underscores the urgent need for robust immunization programmes and global cooperation to achieve the goal of complete polio eradication by 2023, as outlined in the Immunization Agenda 2030 (IA2030).
The Polio Eradication Journey
Polio, a debilitating and potentially fatal disease, has been targeted for global eradication since the launch of the Global Polio Eradication Initiative (GPEI) in 1988. Thanks to widespread vaccination efforts, wild poliovirus cases have decreased by over 99%, with only a handful of cases reported annually in Afghanistan and Pakistan. The IA2030 highlights the importance of strong immunization programmes integrated into primary health care to sustain these gains and prevent resurgence.
The Rise of Vaccine-Derived Poliovirus
While the oral polio vaccine (OPV) has been instrumental in reducing wild poliovirus, it contains a weakened live virus that, in rare cases, can mutate and regain virulence. This mutated form, known as vaccine-derived poliovirus (VDPV), can spread in communities with low vaccination coverage, leading to outbreaks. Recent cases have been reported in Africa, Asia, and even in countries like the United States and the United Kingdom, where polio was once considered eliminated.
The IA2030 emphasizes that VDPV outbreaks are a stark reminder of the need for high vaccination coverage and robust surveillance systems. The document notes that interrupting VDPV transmission requires the same urgency as eradicating wild poliovirus, with a target to stop outbreaks within 120 days of detection.
Challenges in Conflict Zones and Underserved Areas
The persistence of polio in Afghanistan and Pakistan is exacerbated by conflict, weak health infrastructure, and difficulties in reaching children in remote or insecure areas. Similarly, VDPV outbreaks often occur in regions with fragile health systems, where immunization programmes are inconsistent. The IA2030 calls for tailored strategies to reach zero-dose children, those who have never received any vaccines, and to address gender-related and socioeconomic barriers to access.
The Way Forward
To combat both wild poliovirus and VDPV, the IA2030 proposes strengthening immunization programmes by integrating polio vaccination into primary health care to ensure sustainable coverage. It also calls for enhancing surveillance systems for rapid detection and response to outbreaks, using lessons learned from measles and other disease control initiatives.
The document recommends gradually transitioning from OPV to the inactivated polio vaccine (IPV) to eliminate the risk of VDPV. It further highlights the need for global collaboration, aligning efforts across governments, NGOs, and international organizations to maintain funding and political commitment.
The fight against polio is at a critical juncture. While the end of wild poliovirus is within reach, the rise of VDPV poses a significant hurdle. As the IA2030 underscores, leaving no one behind in immunization efforts is essential to achieving a polio-free world. The global community must remain vigilant, innovative, and united to ensure that decades of progress are not undone by emerging threats.
Call to Action
Governments, health agencies, and communities must prioritize vaccination campaigns, especially in high-risk areas, and invest in health systems to prevent future outbreaks. The IA2030’s vision of a world where everyone benefits from vaccines depends on it.
