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Out-Of-State Visitors Most Likely To Spread COVID-19 In Pitkin County, Study Shows

Aug 3, 2020

Cell phone mobility data, cross-referenced with COVID-19 rates in different parts of the country, shows that the most likely spreaders of coronavirus in Pitkin County are from Texas.
Credit Alex Hager / Aspen Public Radio

Pitkin County is using a study of cell phone data to figure out who is most likely to spread COVID-19 within the county. 

The numbers are a combination of how many people from a specific place are in Pitkin County and how prevalent the virus is in their home region. 

In late July, the most likely spreaders of COVID-19 were from Texas. Second is “Rest of USA,” a combination of other states that each posted small individual numbers. Pitkin County residents are third, with Florida residents close behind.

The most recent data is from July 23rd. Only about one month earlier, data from June 25th showed Pitkin County and Garfield County residents as the most likely to spread the virus. Texas ranked third and “Rest of USA” was fourth. 

 

 

This chart, presented in a Pitkin County Board of Health Meeting, shows an increase in the chances that out-of-county visitors spread coronavirus
Credit Screenshot from Pitkin County Board of Health

Pitkin County epidemiologist Charlie Spickert emphasized that the statistics do not purely represent visitor traffic, but also factor in the prevalence of disease in the places where visitors and locals reside. 

“It’s partly the frequency that you’re going to run in to one of those individuals,” Spickert said.  “And secondly, depending on the prevalence of the disease at the point they come from, what’s the chance that that random encounter would be with someone that has COVID-19.”

Spickert said this summer’s visitorship is similar to years past, but the high prevalence of disease in the southern U.S. pushes Texas and Florida to the top of the list. 

He added that the data can be used to inform mitigation strategies – such as quarantine policies and informational campaigns for arriving visitors. 

The statistics are calculated using cell phone mobility data from an information collective called SafeGraph, then shared with the county via the Colorado Department of Public Health and Environment.