J Infect DisJ Infect DisjidThe Journal of Infectious Diseases0022-18991537-6613Oxford University PressUS33885734808322710.1093/infdis/jiab160jiab160Major ArticleAcademicSubjects/MED00290Updated characterization of poliovirus transmission in Pakistan and Afghanistan and the impacts of different outbreak response vaccine optionsKalkowskaDominika A1PallanschMark A2CochiStephen L3ThompsonKimberly M1 Kid Risk, Inc., Orlando, FL, USA National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA, USA Global Immunization Division, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, USAPlease address correspondence to: Dr. Kimberly Thompson, Kid Risk, Inc., 7512 Dr. Phillips Blvd. #50-523, Orlando, FL 32819, USA, Email: kimt@kidrisk.org2242021jiab1602712021Published by Oxford University Press for the Infectious Diseases Society of America 2021.2021This article is made available via the PMC Open Access Subset for unrestricted re-use and analyses in any form or by any means with acknowledgement of the original source. These permissions are granted for the duration of the COVID-19 pandemic or until permissions are revoked in writing. Upon expiration of these permissions, PMC is granted a perpetual license to make this article available via PMC and Europe PMC, consistent with existing copyright protections.This work is written by (a) US Government employee(s) and is in the public domain in the US.AbstractBackground

Pakistan and Afghanistan remain the only reservoirs of wild poliovirus transmission. Prior modeling suggested that before the COVID-19 pandemic, plans to stop the transmission of serotype 1 wild poliovirus (WPV1) and persistent serotype 2 circulating vaccine-derived poliovirus (cVDPV2) did not appear on track to succeed.

Methods

We updated an existing poliovirus transmission and Sabin-strain oral poliovirus vaccine (OPV) evolution model for Pakistan and Afghanistan to characterize the impacts of immunization disruptions and restrictions on human interactions (i.e., population mixing) due to the COVID-19 pandemic. We also consider different options for responding to outbreaks and for preventive supplementary immunization activities (SIAs).

Results

The modeling suggests that with some resumption of activities in the fall of 2020 to respond to cVDPV2 outbreaks and full resumption on January 1, 2021 of all polio immunization activities to pre-COVID-19 levels, Pakistan and Afghanistan would remain off-track for stopping all transmission through 2023 without improvements in quality.

Conclusions

Using trivalent OPV (tOPV) for SIAs instead of serotype 2 monovalent OPV (mOPV2) offers substantial benefits for ending the transmission of both WPV1 and cVDPV2, because tOPV increases population immunity for both serotypes 1 and 2 while requiring fewer SIA rounds, when effectively delivered in transmission areas.

polioeradicationdynamic modelingoutbreak responsearticle-lifecyclePAPedited-stateaccepted-manuscript