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714 www. thelancet. com Vol 400 September 3, 2022 risk of vaccine-associated paralytic poliomyelitis caused by Sabin 2. 6 Although most countries eliminated Sabinlike poliovirus type 2 (SL2) transmission following the switch, some cVDPV2 transmission continued, leading to sporadic cVDPV2 outbreaks as poliovirus type 2 mucosal immunity declined. 7, 8 Sabin monovalent OPV type 2 (mOPV2) was used to address these outbreaks, but many such campaigns were delayed and provided insufficient coverage, leading to further emergence and transmission of cVDPV2. 8, 9 The COVID-19 pandemic compounded the issue; routine polio vaccination, surveillance, and cVDPV2 outbreak response activities were suspended for 4 months in 2020 to protect communities and health workers, enabling further spread of cVDPV2. 8 Furthermore, many of the large cVDPV2 outbreaks have emerged in countries …