Progress Toward Poliomyelitis Eradication - Afghanistan, January 2021-September 2022

Abstract

Afghanistan and Pakistan are the two remaining countries with endemic wild poliovirus type 1 (WPV1) transmission (1). During 2019-2020, these countries reported their highest numbers of WPV1 cases since 2014 and experienced outbreaks of type 2 circulating vaccine-derived poliovirus (cVDPV2) (2-4).* In Afghanistan, the number of WPV1 cases nearly doubled, from 29 in 2019 to 56 in 2020; 308 cVDPV2 cases were reported during 2020. After years of active conflict, the Afghanistan government was fully replaced by the Taliban de facto government on August 15, 2021. This report describes activities and progress toward polio eradication in Afghanistan during January 2021-September 2022 and updates previous reports (3,4). During January-December 2021, four WPV1 and 43 cVDPV2 cases were detected, representing decreases of 93% from 56 cases and 86% from 308 cases, respectively, during 2020. During January-September 2022 (reported as of October 20), two WPV1 cases and zero cVDPV2 cases were detected. Although no supplementary immunization activities (SIAs)^† occurred during July-October 2021, SIAs resumed during November 2021 in all districts after the political transition, and 3.5-4.5 million previously unreachable persons have been vaccinated since. However, restrictions on how SIAs are conducted are still in place in the critical South Region provinces of Kandahar, Helmand, and Uruzgan. If efforts to vaccinate all children are enhanced and expanded, Afghanistan has an opportunity to interrupt WPV1 transmission during 2023.

FIGURE 1

Number of wild poliovirus type 1 cases and circulating vaccine-derived poliovirus type 2^, cases, by month of onset of paralysis — Afghanistan, January 2019–September 2022 Abbreviations: cVDPV2 = circulating vaccine-derived poliovirus type 2; WPV1 = wild poliovirus type 1. * The number of cases of WPV1 and cVDPV2 were 90 and 351, respectively. ^† cVDPVs are genetically linked VDPV2 isolates for which there is evidence of person-to-person transmission in the community. ^§ Data as of October 20, 2022.

FIGURE 2

Cases of polio caused by wild poliovirus type1 and circulating vaccine-derived poliovirus type 2, by province and period — Afghanistan, January 2021–September 2022^, Abbreviations: cVDPV2 = circulating vaccine-derived poliovirus type 2; WPV1 = wild poliovirus type 1. * cVDPVs are genetically linked VDPV2 isolates for which there is evidence of person-to-person transmission in the community. ^† Total cases by period: January–June 2021 = one WPV1 and 42 cVDPV2, July–December 2021 = three WPV1 and one cVDPV2, and January–September 2022 = two WPV1 and zero cVDPV2. ^§ Data as of October 20, 2022.