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Video illustrates the 'dynamic' spread of coronavirus in Tucson
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Video illustrates the 'dynamic' spread of coronavirus in Tucson

From the May's Tucson-area coronavirus coverage: Cases rise, judge rules that state can keep nursing home data from public series

Researchers from the University of Arizona catalog blood samples taken for antibody testing. The first phase of the testing began Thursday with 3,000 health-care workers and first responders. The goal is to test 250,000 first responders and health-care workers statewide.

A new video illustrating the spread of COVID-19 in the Tucson-area shows how the virus has moved in and out of the community over the last two months.

The video, posted to the Pima County Health Department’s Facebook page Wednesday, uses red dots to map the general location of positive cases in Pima County over time. As each dot ages beyond 15 days, it falls off the map to show the cases that are no longer infectious. New cases, represented by new red dots, surface on the map as quickly as others disappear.

“One of the things that is not clear with the maps available on the Arizona Department of Health Services website is that because the number of cases are growing, it doesn’t give you a sense of how those cases change over a period of time,” said Pima County’s Chief Medical Officer Francisco Garcia. “We wanted to give folks a sense of how a case appears in our community and how it disappears from our community. We know that people are infectious for at least 14 days, and this was a way of portraying the fact that at some point, all those cases will stop being infectious.”

The first dot on the map appears Feb. 18 and is located south of Sahuarita. The next dot appears on Feb. 22 near Cienega High School on the far east side of the county. As the time-lapse continues through April 24, the dots eventually cover almost every populated area in Pima County. The map does not include cases located on Indian reservations.

“This is a really dynamic situation, and it’s impacting every single corner of Pima County,” Garcia said. “Cases are being identified every day, and other cases are disappearing.”

Although health officials are assuming that someone will stop being infectious after 14 days, Garcia said this can vary and that they are still trying to determine when someone can be declared recovered. There is some evidence that people who are immunosuppressed and people who are older may be infectious for longer than 14 days, and there are also people who will be infectious for fewer than 14 days.

According to Garcia, the data may also be skewed because they start counting from the day that someone was tested, not necessarily from the day that their symptoms began. So, if someone didn’t seek medical care until their fourth day of symptoms, they could stop being infectious sooner than the data will show.

“We will overestimate some, and we will underestimate others, but hopefully what we are portraying is a dynamic representation of how this infection is moving in and out of our community and the fact that it’s really affecting every single geographic segment of Pima County,” Garcia said.

Even with the decision to extend Arizona’s stay-at-home order through May 15, Gov. Doug Ducey announced Thursday that he will allow certain businesses to reopen with certain restrictions as early as Monday, May 4. This has community members wondering when social distancing standards will relax even further.

For Garcia, the fight isn’t over yet, however. Pima County still has not reached a point in the curve that would make health officials comfortable with a full reopen. Garcia said it’s important that community members stay patient and continue following the protocols.

“The reason that we have not overwhelmed our hospital system and why we have not had more cases and more deaths is because this community has been able to achieve a fairly high degree of social distancing,” he said. “We’re hoping that this kind of information encourages people to continue doing the same because we need that in order to get to the downward slope of that infection curve.”

Contact reporter Jasmine Demers at

On Twitter: @JasmineADemers.

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