Since October 2016, Afghanistan and Pakistan have been the only countries with reported cases of wild poliovirus type 1 (WPV1) (1). In Afghanistan, although the number of cases had declined during 2013-2016, the polio eradication program experienced challenges during 2017-2019. This report describes polio eradication activities and progress in Afghanistan during January 2018-May 2019 and updates previous reports (2,3). During May-December 2018, insurgent groups (antigovernment elements) banned house-to-house vaccination in most southern and southeastern provinces, leaving approximately 1 million children inaccessible to oral poliovirus vaccine (OPV) administration. During January-April 2019, vaccination targeting children at designated comm...