Response to back-to-back outbreaks of circulating vaccine-derived poliovirus type 2 in two nomadic pastoralist settlements in Oti Region, Ghana-2019.

Background: The global switch from trivalent oral poliovirus vaccine (OPV) to bivalent OPV in April 2016 without corresponding co-administration of inactivated poliovirus vaccine (IPV) until June 2018, created a cohort of poliovirus type 2 naïve children with risk of developing vaccine-derived poliovirus type 2 (VDPV2). In November and December 2019, two cases of circulating vaccine-derived poliovirus type 2 (cVDPV2) were confirmed in quick succession through Acute Flaccid Paralysis (AFP) surveillance in two nomadic pastoralist settlements in Oti Region. We investigated to determine the outbreak extent, identify risk factors and implement control and preventive measures.