Modeling Strategies to Increase Population Immunity and Prevent Poliovirus Transmission in Two High-Risk Areas in Northern India

Modeling Strategies to Increase Population Immunity and Prevent Poliovirus Transmission in Two High-Risk Areas in Northern India
by Dominika A. Kalkowska, Radboud J. Duintjer Tebbens, and Kimberly M. Thompson, Journal of Infectious Diseases 2014; 210(S1):S398-411.
Technical Appendix

Answers to frequently asked questions

What are the study’s main findings?
What are the study’s main recommendations?
Background on polio

What are the study’s main findings?

Immunization policy choices impact population immunity in northern India, which leads to different numbers of expected paralytic cases and risks of circulating vaccine-derived poliovirus (cVDPV) outbreaks.
We do not anticipate a high risk of serotype 2 cVDPV emergences following coordinated cessation of serotype 2-containing oral poliovirus (OPV2 cessation) if northern India maintains intense vaccination everywhere, including its use of tOPV SIAs and maintenance of efforts to reach previously under-vaccinated subpopulations.
However, gradually reducing SIAs leads to a substantial decrease in population immunity and a risk of large cVDPV outbreaks that would preclude successful OPV cessation.
Adding a dose of inactivated poliovirus vaccine (IPV) before or at the time of OPV2 cessation provides a modest increase in population immunity and little impact in cVDPV risks, but shows a notable reduction in expected cVDPV cases in potential scenarios in which these would occur.

What are the study’s main recommendations?

Northern India must sustain high population immunity with good routine immunization and frequent tOPV SIAs up until OPV2 cessation as well as frequent SIAs with bivalent OPV up until cessation of the other OPV serotypes.
The global tOPV supply should anticipate the need for large amounts of tOPV for Northern India up until OPV2 cessation, regardless of the extent of adoption of IPV in Northern India.
Reaching historically under-vaccinated groups remains critical to avoid local population immunity gaps that could result in cVDPV emergences.