Successes and Shortcomings of Polio Eradication: A Transmission Modeling Analysis

Abstract

Polio eradication is on the cusp of success, with only a few regions still maintaining transmission. Improving our understanding of why some regions have been successful and others have not will help with both global eradication of polio and development of more effective vaccination strategies for other pathogens. To examine the past 25 years of eradication efforts, we constructed a transmission model for wild poliovirus that incorporates waning immunity (which affects both infection risk and transmissibility of any resulting infection), age-mediated vaccination rates, and transmission of oral polio vaccine. The model produces results consistent with the 4 country categories defined by the Global Polio Eradication Program: elimination with no subsequent outbreaks; elimination with subsequent transient outbreaks; elimination with subsequent outbreaks and transmission detected for more than 12 months; and endemic polio transmission. Analysis of waning immunity rates and oral polio vaccine transmissibility reveals that higher waning immunity rates make eradication more difficult because of increasing numbers of infectious adults, and that higher oral polio vaccine transmission rates make eradication easier as adults become reimmunized. Given these dynamic properties, attention should be given to intervention strategies that complement childhood vaccination. For example, improvement in sanitation can reduce the reproduction number in problematic regions, and adult vaccination can lower adult transmission.

Epidemiology of the silent polio outbreak in Rahat, Israel, based on modeling of environmental surveillance data

“…of the outbreak (R(0) = 0). Our simulation spans less than 1 y, so we neglect waning immunity and vital dynamics (25). Susceptible individuals can be vaccinated at a rate ϕ, becoming latently infected with the vaccine strain (E v o ), or can be infected via transmission, becoming latent with the WPV1 (E t w ) or OPV1 strain (E t o ).…”

The differential impact of oral poliovirus vaccine formulation choices on serotype-specific population immunity to poliovirus transmission

“…Second, our model relies on sets of generic model inputs based on an expert literature review process [ 22 , 28 , 31 ] that fits the evidence across a wide range of situations [ 9 , 17 ] but that does not preclude the possibility that other combinations of generic model inputs may produce results overall consistent with the evidence. For example, the kinetics of waning remain uncertain and intestinal immunity may wane more steeply after 5 or more years [ 32 ] than assumed in our model [ 17 ] based on the limited evidence [ 28 , 31 , 33 ], which would result in more cVDPV emergences and cases both before and after OPV2 cessation. Thus, further empirical evidence and study of model uncertainties would further help inform decisions.…”

Data Integration and Predictive Analysis System for Disease Prophylaxis

“…Prior knowledge of potential disease occurrences enables proactive development of medical interventions, medical prophylaxis to disease hazards, and containment of disease vectors. Traditional epidemiology has focused on compartmental models (susceptibility, exposed, infected, recovered (SEIR) based approaches for forecasting disease progression [4,5,6]), which are data and modelling intensive. IPAS takes advantage of innovative machine learning and predictive analytics to facilitate creation of generic disease prediction models.…”