Polio Cases Surge in July 2024

While efforts to eradicate poliomyelitis have been ongoing for decades, significant progress has been made in reducing polio cases by 99% over the last 30 years.

However, the last steps in eradicating the disease are proving to be the most challenging, as recent data indicates a resurgence of polio in 2024.

According to the latest Global Polio Eradication Initiative (GPEI) report, five countries reported new polio cases this week.

As of July 24, 2024, Pakistan reported a wild poliovirus type 1 (WPV1) case. This is the ninth WPV1 case reported in Pakistan this year.

And vaccine-derived cases were detected in the Democratic Republic of the Congo (1), Ethiopia (5), Somalia (1), and Yemen (11).

Last week, the GPEI reported that Nigeria confirmed one circulating vaccine-derived poliovirus type 2 (cVDPV2) case. There have been 31 cases reported this year and 87 cases reported in 2023.

The GPEI says cVDPV2 is a public health threat that affects 27 countries, including Angola, Liberia, Senegal, Sierra Leone, and South Sudan, located across four World Health Organization (WHO) regions.

Based on the current situation regarding WPV1 and cVDPVs and the reports provided by affected countries, the WHO Director-General determined in April 2024 that poliovirus detections continue to constitute an emergency.

cVDPV cases are associated with oral polio vaccines (OPV) and can cause paralysis among persons in areas with low population immunity to polioviruses.

To address this issue, the novel oral polio vaccine (nOPV2) is being rolled out under the WHO Emergency Use Listing (November 2020). The nOPV2 is reported to be more genetically stable than previous OPVs, with a lower risk of reversion to neurovirulence and less likely to mutate and cause paralysis.

On February 28, 204, the U.S. CDC Advisory Committee on Immunization Practices included an Introduction and Considerations for the Potential Use of nOPV2 as an Outbreak Control Measure.

The nOPV2 vaccine is not yet approved by the U.S. FDA.

As of July 2024, over 1 billion doses of nOPV2 have been administered worldwide, says the GPEI.

However, 14.3 million children were missing out on any vaccination in 2022. To reduce the number of polio cases, these so-called “zero-dose children” also need access to polio vaccines.

The WHO strongly recommends that these children be offered disease-prevention vaccines in 2024.