Support of Global Polio Eradication Initiative (GPEI) using Integrated Modeling

Nations Children’s Fund (UNICEF), the Bill and Melinda Gates Foundation (BMGF), and Gavi, the Vaccine Alliance. The GPEI has made tremendous progress toward global eradication with WPV circulating in only 2 countries in 2020, Afghanistan and Pakistan, down from 125 countries in 1988. WPV type 2 and 3 have been successfully certified as eradicated with only type 1 WPV remaining. With the certification of WHO’s African Region as free of WPV on August 25, 2020, five of WHO’s six Regions are now declared WPV free. Only the Eastern Mediterranean Region has yet to achieve this goal. The GPEI now faces two major challenges: 1) continued transmission of WPV1 in Pakistan and Afghanistan and 2) an increasing number of outbreaks of circulating Vaccine Derived Polioviruses (cVDPVs) which result from prolonged circulation in under-immunized communities of the live weakened virus from the oral poliovirus vaccine (OPV). Kid Risk and CDC have collaboratively addressed complex polio eradication issues for almost 20 years to inform policymaking by CDC and GPEI. The work completed under the most recent cooperative agreement (NU2RGH001913) included updates to the global integrated economic, risk and dynamic disease model to reflect the current GPEI strategic planning and implementation efforts to characterize poliovirus transmission and assess the health and economic trade-offs associated with different policy options. Kid Risk's expanded and updated poliovirus transmission model accounts for differences in serotype and transmission routes, routine childhood immunization schedules, Sabin OPV evolution in transmission and the emergence of cVDPVs, particularly type 2 (cVDPV2). During 2019, Kid Risk focused on characterizing WPV transmission in Borno and Yobe states of northeast Nigeria and the confidence in the available evidence of no transmission of WPV, to inform the Africa Region Certification Commission’s evaluation of certifying the region WPV-free. In addition, in 2020, they have modeled the changing cVDPV2 epidemiology and risk of different response strategies that may result in restarting Sabin type 2 in routine immunization schedules, and what potential outcomes are possible with wide scale use of a novel, stabilized type 2 OPV. Numerous key questions about the polio eradication endgame remain, particularly the best vaccine strategies to address cVDPV2 outbreaks and ultimately withdraw all use of Sabin OPV. At this stage of the GPEI, modeling of new strategies is required, particularly with respect to use of a stabilized, novel OPV type 2 and other outbreak strategies to stop and prevent VDPV2 outbreaks, as well as how to achieve WPV eradication in Pakistan and Afghanistan. This announcement requests the awardee to expand upon their work as part of CDC's GPEI support, as well as modeling issues regarding control and elimination of other VPDs.