The good news is that the global effort to eradicate polio has made significant progress over the past few decades and that the number of cases of both wild poliovirus and vaccine-derived poliovirus has dramatically decreased. The vast majority of the world’s population (99.99%+) is now free of polio, thanks to widespread vaccination efforts.
The bad news is that vaccine-derived polio (VDPV) is a rare but significant threat to the global effort to eliminate polio. VDPV is a strain of the poliovirus that has genetically mutated from the attenuated (weakened) strain used in the oral polio vaccine (OPV), and it can cause outbreaks of polio in populations with low vaccination coverage. Vaccine-derived poliovirus is rare but can emerge in under-vaccinated populations where the oral polio vaccine (OPV) is still in use. OPV contains a weakened form of the virus that can sometimes mutate and become virulent, leading to the emergence of vaccine-derived poliovirus.
While the OPV has been critical in reducing the incidence of polio globally, it carries a risk of causing VDPV in rare cases. The World Health Organization (WHO) and its partners are working to mitigate this risk by switching from trivalent OPV (tOPV) to bivalent OPV (bOPV) in routine immunization activities. This switch reduces the likelihood of VDPV emergence because the trivalent vaccine contains all three types of poliovirus, while the bivalent vaccine contains only the two remaining types (type 1 and 3).
Despite these efforts, however, VDPV outbreaks have occurred in recent years in several countries, including Afghanistan, Pakistan, Nigeria, and the Democratic Republic of the Congo. To address this threat, the Global Polio Eradication Initiative (GPEI) developed a comprehensive strategy to detect and respond to VDPV outbreaks quickly. This strategy includes strengthening surveillance systems to detect cases, conducting mass immunization campaigns in affected areas, and implementing other measures to ensure high vaccination coverage.
As of September 2021, vaccine-derived polio (VDPV) is present in a few countries worldwide. According to the World Health Organization (WHO), as of August 2021, 25 countries have reported cases of circulating vaccine-derived poliovirus (cVDPV), with a total of 852 cases reported globally. The majority of these cases were reported in Afghanistan and Pakistan.
Overall, the elimination of wild poliovirus will require sustained efforts, political commitment, and sufficient resources. The 2026 target for elimination is ambitious and achievable if current practices and projections are maintained and improved.
To eliminate wild poliovirus by 2026, the GPEI needs to focus on improving vaccination coverage, strengthening surveillance and response, engaging communities, securing political commitment, collaborating across borders, exploring innovative strategies, and building and continuing strong partnerships, like the partnership with Rotary International.
To eliminate vaccine-derived polio and achieve the goal of global polio eradication by 2026, the following steps need to be taken:
Strengthening routine immunization – Ensuring high coverage of polio vaccine in routine immunization programs is essential to prevent outbreaks of both wild and vaccine-derived polio.
Strengthening surveillance – Surveillance for acute flaccid paralysis (AFP) is critical to detect any cases of polio, both wild and vaccine-derived, and to guide response activities. Sensitive surveillance systems need to be established and maintained to identify all cases of AFP and to test specimens from suspected cases.
Responding to outbreaks – When cases of polio are detected, rapid response teams need to be deployed to conduct investigations, conduct a thorough risk assessment, and respond with a range of activities, including vaccination campaigns and surveillance enhancement.
Strengthening routine immunization of high-risk populations – High-risk populations, such as nomads, refugees, and migrant workers, need to be reached through targeted immunization activities to ensure they are adequately protected against polio.
Improving vaccine coverage in low-income settings – Vaccine coverage needs to be improved in low-income settings where children may have limited access to health services or where health infrastructure is weak.
Strengthening health systems – Strengthening health systems is essential to ensure that immunization programs are sustainable and can continue to deliver vaccines even after the goal of polio eradication is achieved.
Developing new vaccines – The development of new vaccines that are more effective against all types of polio, including vaccine-derived polio, is important to ensure sustained polio eradication.
There are ongoing efforts to develop new and improved vaccines against polio, including vaccine-derived polio (VDPV). One such vaccine is the novel oral polio vaccine type 2 (nOPV2), which is designed to be more effective against all types of polio, including VDPV.
nOPV2 has been developed through a collaboration between the World Health Organization (WHO), the Bill and Melinda Gates Foundation, and various vaccine manufacturers. Clinical trials have shown promising results, and the vaccine is currently undergoing further testing and evaluation to ensure its safety and efficacy while it is under emergency use in at least 16 countries. It is anticipated that it will be regularly available for use in 2023. This depends on factors such as regulatory approval, manufacturing capacity, and global distribution networks. However, the WHO and its partners, including Rotary International, are working to accelerate the development and deployment of new polio vaccines as part of ongoing efforts to achieve sustainable polio eradication by 2026.
By implementing these measures, it truly is possible to eliminate vaccine-derived polio and achieve the goal of global polio eradication by 2026.*
Almost a decade ago, when I first discovered this information while working as a temporary COO for Snohomish Health District [in charge on a daily basis of business functions, policy revision, community health programs, waste sites, septic, water, and food permits; as well as infectious disease prevention, including vaccinations, TB, pertussis, and numerous diseases I’d never heard of…], I was shocked to find out that almost all health district employees had ever heard of Rotary’s involvement in this project!
And yet, health district employees were vitally interested and engaged in polio eradication. Today, Rotary International has mastered both polio eradication and media recognition for fair, equitable, and just recognition of Rotary’s longitudinal role in the polio eradication project. You can be sure that his recognition is partly due to Rotary International’s contemporary media sophistication and partly due to the Bill and Melinda Gates Foundation, which regularly matches Rotary contribution and then adds even greater investment.