By Ethan Covey

The primary tracker for poliovirus transmission, acute flaccid paralysis (AFP) surveillance, bounced back during 2021, after COVID-19 pandemic-related drops in 2020.

Although gaps still exist, the findings show the success of continued efforts to achieve polio eradication (MMWR Morb Mortal Wkly Rep 2022;71:538-544).

“We are closer than ever to eradicating wild poliovirus and protecting future generations of children around the world,” Amanda L. Wilkinson, PhD, an epidemiologist with the Polio Eradication Branch, Global Immunization Division, CDC’s Center for Global Health, told Infectious Disease Special Edition.

“This update shows that we are going in the right direction in terms of improving surveillance in key areas, but we can’t afford to stop now,” Dr. Wilkinson added. "The ‘last mile’ is always the hardest, and we must continue to strengthen surveillance systems and our ability to quickly and robustly respond when cases of polio are confirmed.”

Reported AFP cases fell by 33% from 2019 to 2020, coinciding with the arrival of the COVID-19 pandemic. Environmental sampling of sewage, a second key component of polio surveillance, also declined (MMWR Morb Mortal Wkly Rep 2021;69:1648-1652).

However, analysis of 2021 AFP data showed significant improvements compared with 2020. In 43 countries identified as experiencing or being at high risk for poliovirus transmission, 74% met two key surveillance performance indicator targets nationally, more than 53% during 2020. Additionally, several countries, including Burkina Faso, Côte d’Ivoire, Democratic Republic of the Congo and Niger, showed improved surveillance in 2021 over pre-pandemic levels.

“Strong, high-performing poliovirus surveillance is critical to detecting infections, tracking transmission and eradicating polio,” Dr. Wilkinson said. “Frequent monitoring of surveillance indicators is helping us to identify gaps, guide improvements and enhance the overall sensitivity (ability to detect polio) and time lines for polio detection. The updated Global Polio Surveillance Action Plan for 2022-2024 was developed to guide and monitor surveillance system improvements at all levels of the Global Polio Eradication Initiative.”