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COVID-19 models: What do they say about Arizona?

UArizona COVID-19 model - April 8 2020
Posted at 5:05 PM, Apr 10, 2020
and last updated 2020-04-11 00:03:51-04

COVID-19 models. We hear about them at press briefings by state and federal officials. They can be found everywhere online, from the Imperial College of London model that was first used to sound the alarms around the world, to the University of Washington model, that is being utilized by several states, including our own, to manage --and anticipate -- hospital resource allocation.

What do they mean? And what do the models tell us about the potential impact COVID-19 could have on Arizona?

Kate Ellingson is an assistant professor of epidemiology and biostatistics at the University of Arizona. She is part of a team that is modeling COVID-19 for its potential impact on both Arizona and Pima County, which covers parts of southwestern Arizona and Tucson.

View UArizona's COVID-19 model

Each week they post updated versions of the model using the previous week's COVID-19 reports from the Arizona Department of Health Services. From there, the model adjusts. She told ABC15 that their model also uses information from public models, such as the Washington model mentioned above, and COVID ACT Now, another model.

Ellington said there is a reason they are taking all of these models into account.

While the goal of all the models is to predict the strain and impact that COVID-19 could put on the healthcare system, the models can take different paths and come up with different results.

The University of Washington model relies on the number of COVID-19-related deaths that states report to judge the number of hospital and ICU beds that will be needed in the future. Whereas, the COVID Act Now model, relies on more traditional approaches of looking at data from areas of the world that are either in "peak" COVID-19 cases or past their COVID-19 “epi curve”.

The difference between the two is stark. The Washington model projects a total of 974 COVID-19-related deaths in Arizona by August 4th, while the Covid Act Now model projects 3,000 to 77,000 deaths.

As of this writing, there have been 92 deaths connected to COVID-19 in Arizona, according to the Arizona Department of Health Services. There have been more than 3,000 confirmed cases.

Ellingson said that as more data on COVID-19 infections becomes available -- something that is expected to occur on Sunday, April 12, when AZDHS begins to provide zip code as well as race/ethnicity data on COVID-19 infections -- researchers at UArizona will begin to develop additional models to understand the social aspects of COVID-19 infections.

They will be looking at whether factors like jobs, population density, and reliance on public transportation have any effect on the likelihood of someone contracting COVID-19.

One question that Ellingson has, and quite frankly one that we all have, is when will social distancing guidelines be lifted?

She does believe that while Arizona is successfully "flattening the curve", what the models are not showing is the possibility of second or third waves of COVID-19. What does that look like? What impact could that have on Arizona?

Those are questions many are still trying to answer.