The Global Polio Eradication Initiative (GPEI), launched 34 years ago, aimed to eradicate poliomyelitis by 2000. The chosen strategy was to stop circulation of wild polioviruses, following the successful example of smallpox eradication. The task, however, turned out to be much more challenging than eradicating smallpox had been, since there are hundreds of asymptomatic poliovirus infections for each paralytic case that occurs, which substantially complicates critical surveillance. Aside from challenges inherent in vaccine delivery in some countries, another reason for the failure to eradicate polio were outbreaks caused by circulating vaccine-derived poliovirus (cVDPV) strains that emerged from viruses used in Oral Polio Vaccine (OPV). Thus, to actually eradicate poliovirus, the use of OPV must also be stopped.

The recent declaration of a public health emergency in New York State after a case of paralytic poliomyelitis caused by a cVDPV, along with cVDPV detection in wastewater both in New York and in London, is a sobering reminder that polio still represents a threat even in countries that have not seen it for decades. Silent circulation of poliovirus was not unexpected: such circulation was previously observed in countries using inactivated polio vaccine (IPV). Unlike OPV, IPV does not induce the robust mucosal immunity that is important for preventing circulation. The continued circulation of wild and attenuated polioviruses suggests that the approach used by the polio-eradication campaign needs re-evaluation.1

References

  1. Chumakov, K., Brechot, C., Gallo, R. C., & Plotkin, S. (2023). Choosing the Right Path toward Polio Eradication. The New England Journal of Medicine, 388(7), 577–579. https://doi.org/10.1056/nejmp2215257

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