MS02 - MEPI-12

Incorporating control into infectious disease models

Monday, July 14 at 3:50pm

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Michael A. Robert (Virginia Tech)

Description:

Mathematical models are important for designing and evaluating control strategies for infectious diseases. Models are useful for proposing new control strategies, comparing strategies against one another, and assessing the efficacy of strategies that were implemented during outbreaks. Model results can then be used to inform policy at multiple organization levels from regional approaches to outbreak response to optimization of resources for managing large outbreaks. In this mini-symposium, we review recent modeling work that focuses on control of infectious diseases and the factors that contribute–or impede–successful control. The talks in the mini-symposium will address issues in control related to pathogens, the environment, population heterogeneities, and host behavior.

Stacey Smith?

University of Ottawa

"Could COVID-19 mask and vaccine mandates have made a difference if they were rolled out earlier?"

Hospitalizations and deaths due to COVID-19 in Canada declined after the first wave, thanks to nonpharmaceutical interventions and the vaccination campaign starting in December 2020, despite the emergence of highly contagious variants. We used an age-structured extended Susceptible-Exposed-Infected-Recovered compartment model to mimic the transmission of COVID-19 in Ontario from March 1, 2020 to May 31, 2021. We examined several counterfactual scenarios: 1. No mask mandates; 2. No vaccination; 3. Instigating the mask mandate a month earlier; 4. Rolling out the vaccine a month earlier. A one-month-earlier vaccination program could have significantly decreased the number of cases and hospitalizations, but one-month-earlier mask mandates would not have. It follows that the mandates that were implemented in practice were not optimal, but mostly performed well. Our model demonstrates that mask mandates played a vital role in saving lives in the first wave of the COVID-19 outbreak and that the vaccination program was crucial to averting subsequent cases and hospitalizations after it was implemented.

Indunil M. Hewage

Washington State University

"The population-level impact of COVID-19 vaccines: Investigating the different aspects of vaccine effectiveness."

Vaccination programs have helped reduce case numbers and the death toll of COVID-19 significantly over the past few years. The spread and control of COVID-19 have been studied by means of ODE-based compartmental models in a number of studies. However, studies on the different benefits of vaccines, other than blocking infections, remains a paucity. In this study, we developed an ODE-based compartmental model with a separate disease progression path for vaccinated individuals. Several key parameters for the vaccinated individuals were defined in terms of the respective parameters for the non-vaccinated individuals to account for the different facets of vaccine effectiveness: blocking infections; decreasing transmission; expediting recovery; reducing severe morbidity; and preventing disease mortality. Sensitivity analyses and numerical simulations on the reproduction number, infections, and disease-induced deaths provided important insights into the impact of different aspects of vaccine effectiveness on disease control. Disease burden can be reduced drastically with vaccines that have high potential in blocking infections, reducing infectivity, and speeding up recovery.

Carrie Manore

Los Alamos National Labs

"Designing Models and Forecasts with Non-Traditional Data to Assess Interventions and Prevention"

As the world becomes more connected and ecosystems change, we need adaptive tools to asses how risk is changing and inform options for interventions. We have adapted traditional forecasting and modeling approaches to ingest data that can adapt model parameters and predictions as conditions change. This includes genetic data to capture pathogen evolution and ecosystem or weather data, to fit time varying parameters. Our approach has the potential to increase the accuracy of mathematical or statistical models in predicting changes in dynamics such as the “elbows” in an outbreak or year to year differences in endemic diseases. Examples will include mosquito-borne diseases and seasonal respiratory infections.

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Annual Meeting for the Society for Mathematical Biology, 2025.