Update on Wild Poliovirus Type 1 Outbreak - Southeastern Africa, 2021-2022

What is already known about this topic? The World Health Organization (WHO) African Region was certified as having interrupted indigenous wild poliovirus (WPV) transmission in August 2020. In 2022, an outbreak of WPV type 1 (WPV1) was detected in southeastern Africa. What is added by this report? To date, one WPV1 case was detected in Malawi and eight in Mozambique. These countries and Tanzania, Zambia, and Zimbabwe implemented up to six national and subnational supplementary immunization activities (SIAs) per country and strengthened poliovirus surveillance. What are the implications for public health practice? Further enhancing surveillance, implementing high-quality SIAs, and strengthening routine immunization are essential to stopping WPV1 transmission within 12 months of the first case, thereby preserving the WHO African Region's WPV-free status.