Progress Toward Poliomyelitis Eradication — Worldwide, January 2021–March 2023

Reported Polio Cases and Isolations

Countries reporting WPV cases and isolations. In 2022, the two remaining countries with endemic WPV1 transmission, Afghanistan and Pakistan, reported two and 20 WPV1 cases, respectively (Figure) (Table 1). In Afghanistan, two cases were reported from two provinces, representing a 50% decrease from the four cases reported from two provinces in 2021 (8). The 20 cases reported in Pakistan in 2022 were all from security-compromised districts in Khyber Pakhtunkhwa province, representing a nineteenfold increase over the single case reported in 2021 (9). As of May 5, a single case of WPV1 was reported in the Khyber Pakhtunkhwa province of Pakistan in 2023. The paralysis onset dates of the latest reported WPV1 case in Afghanistan was August 29, 2022, and in Pakistan was February 20, 2023.

In Afghanistan, among 702 sewage samples collected in 2022, 22 (3%) yielded a WPV1 isolate, representing a 14-fold increase in the percentage of isolates from 0.2% (one WPV1 isolate detected in 473 samples) collected during 2021 (Table 2). In Pakistan, among 1,220 sewage samples collected during 2022, 37 (3%) WPV1-positive isolates were detected, a 57% decrease in the percentage of isolates from 7% (65 WPV1 isolates from 887 samples) in 2021. As of May 5, 2023, the latest WPV1 detections by ES were from samples taken on April 3, 2023, in Afghanistan and on February 21, 2023, in Pakistan.

In 2021, a single paralytic WPV1 case in Malawi was genetically linked to virus circulating in Pakistan and was confirmed in February 2022. In 2022, eight WPV1 cases were detected in Mozambique, genetically linked to the Malawi case, with the latest date of paralysis in August 2022 (10).

Countries reporting cVDPV cases and isolations. During January 2021–March 2023, a total of 1,619 cVDPV cases were reported from 36 countries. Six countries reported 225 cVDPV1 cases, 34 countries reported 1,393 cVDPV2 cases, and one country (Israel) reported one cVDPV3 case. DRC, Malawi, Mozambique, Republic of the Congo, and Yemen reported co-circulation of cVDPV1 and cVDPV2, and Israel reported co-circulation of cVDPV2 and cVDPV3. Global cVDPV2 cases decreased by 1.3% in 2022 (673 cases in 20 countries) compared with 2021 (682 cases in 22 countries); the 504 cVDPV cases detected in DRC represent 59% of all globally reported cVDPV cases in 2022. No cVDPV2 cases or ES detections in Afghanistan or Pakistan were reported after July 2021 (7,8). Global cVDPV1 cases increased by 1,056% (185 cases in five countries) in 2022 compared with 16 cases in two countries in 2021.