Update on Immunodeficiency-Associated Vaccine-Derived Polioviruses - Worldwide, July 2018-December 2019.

Since establishment of the Global Polio Eradication Initiative* in 1988, polio cases have declined >99.9% worldwide; extensive use of live, attenuated oral poliovirus vaccine (OPV) in routine childhood immunization programs and mass campaigns has led to eradication of two of the three wild poliovirus (WPV) serotypes (types 2 and 3) (1). Despite its safety record, OPV can lead to rare emergence of vaccine-derived polioviruses (VDPVs) when there is prolonged circulation or replication of the vaccine virus. In areas with inadequate OPV coverage, circulating VDPVs (cVDPVs) that have reverted to neurovirulence can cause outbreaks of paralytic polio (2). Immunodeficiency-associated VDPVs (iVDPVs) are isolated from persons with primary immunodeficiency (PID). Infection with iVDPV can progress to paralysis or death of patients with PID, and excretion risks seeding cVDPV outbreaks; both risks might be reduced through antiviral treatment, which is currently under development. This report updates previous reports and includes details of iVDPV cases detected during July 2018-December 2019 (3). During this time, 16 new iVDPV cases were reported from five countries (Argentina, Egypt, Iran, Philippines, and Tunisia). Alongside acute flaccid paralysis (AFP) surveillance (4), surveillance for poliovirus infections among patients with PID has identified an increased number of persons excreting iVDPVs (5). Expansion of PID surveillance will facilitate early detection and follow-up of iVDPV excretion among patients with PID to mitigate the risk for iVDPV spread. This will be critical to help identify all poliovirus excretors and thus achieve and maintain eradication of all polioviruses.

Progress toward laboratory containment of poliovirus after polio eradication.

BACKGROUND: The first steps (phase 1) toward laboratory containment of poliovirus after eradication are a national survey of biomedical facilities and a global inventory of such facilities retaining wild poliovirus (WPV) infectious and potentially infectious materials. METHODS: We reviewed published reports on national laboratory surveys and inventories of WPV materials from each of the 3 polio-free World Health Organization (WHO) regions (the European Region, completed in 2006; the Western Pacific Region, completed in 2008; and the Region of the Americas, completed in 2010), as well as reports on progress in polio-free countries of the remaining 3 regions (the African Region, the Eastern Mediterranean Region, and the WHO South-East Asia Region). RESULTS: Containment phase 1 activities are complete in 154 of 194 WHO Member States (79%), including all countries and areas of the polio-free regions and most polio-free countries in the remaining 3 regions. A reported 227 209 biomedical facilities were surveyed, with 532 facilities in 45 countries identified as retaining WPV-associated infectious or potentially infectious materials. CONCLUSIONS: Completion of containment phase 1 global activities is achievable within the time frame set by the Polio Eradication and Endgame Strategic Plan 2013-2018.