Idaho Professor Creates COVID-19 Model To Inform Social Distancing Policies

Apr 17, 2020

To make policy decisions related to COVID-19, Idaho relies, in part, on mathematical models developed by university professors.


Benjamin Ridenhour, the professor who developed the model Idaho is primarily using, is an assistant professor of mathematics at the University of Idaho. He worked on disease modeling for the Centers for Disease Control during the 2009 H1N1 pandemic, so was able to answer the request from the Idaho State Board of Education and the Idaho Department of Health and Welfare.

To create the model, Ridenhour used an “SEIR” framework that’s typical in the epidemiology world. It stimulates people moving through "susceptible," "exposed," "infected" and "recovered" categories over the course of an outbreak, based on assumptions and what we know about the disease so far. It takes into account people who are symptomatic and asymptomatic, and also factors in whether people might need hospitalization or ICU care.

“You're tracking how many people are getting infected and how many people are going to the hospital, and trying to see how that matches up with our capacity in the state," Ridenhour said.

 

Ridenhour's model is distinct from the one out of the University of Washington that relies on data from Wuhan, China to make predictions about when a state might hit its coronavirus peak. This one is more Idaho-specific, Ridenhour said, because it considers Idaho’s rural areas and places where the population skews older. 

The data inputs include more information than what’s available on the Governor’s coronavirus website like the zip code of confirmed cases and the onset date of symptoms. That’s all important to have, he said, in order to project accurate outcomes.

“We would like to have our model reflect what’s going on,” he said. 

But Ridenhour is still missing some data from hospitals that he said would make the model even more accurate.

Public officials, including Governor Brad Little’s Coronavirus Working Group, have used the model to assess social distancing restrictions. 

Overall, Ridenhour said, since he’s been monitoring the data and outcomes, he’s noticed how social distancing policies have been working.

“We were able to see pretty quickly in the models, the social distancing is having an effect on slowing the disease down,” he said. 

Policy makers are also using the framework, which can forecast outcomes based on different scenarios, to understand when to lift social distancing restrictions.

Had Gov. Little not extended the stay-at-home order this week, the model showed Idaho’s health system would have likely been overwhelmed a couple weeks later, according to Ridenhour.

The Idaho Department of Health and Welfare and the Governor’s Coronavirus Working Group do not plan on publishing projections from the model.

Find reporter Rachel Cohen on Twitter @racheld_cohen

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