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New COVID Variants Keep Popping Up. Here’s How They’re Tracked In North Texas.

A medical professional in dark blue scrubs administers a coronavirus test to a person in their car at a drive-through vaccination and testing site in Dallas, Texas.
Keren Carrión
The delta variant represents more than 95% of the coronavirus cases being tracked by a UT Southwestern Medical Center doctor.

Over the past few months, North Texas has seen a spike in COVID-19 cases, mostly due to the more contagious delta variant. As the pandemic intensifies, local researchers have begun to monitor all the new variants and track all the different mutations.

Jeffrey SoRelle with UT Southwestern Medical Center studies and analyzes the results of COVID-19 tests. He said cataloging different strains helps him provide input on care and treatment for patients with different variants.

‘The Most Sequenced Virus In All Of History’

Finding new coronavirus variants is a group effort. SoRelle said he believes COVID is “the most sequenced virus in all of history,” and scientists all over the world upload their sequences for others to view.

“I can go in and say, in New York, California, the UK, what is the most common variants that they're seeing?” SoRelle said. “Or what are the most rapidly increasing variants they're seeing? And are we seeing anything like that here in Texas?”

SoRelle said the first thing he identifies when analyzing a variant is whether it is more infectious. He also looks at how the strain is spreading. When at least 20% of cases in an area are one specific variant — it’s considered a “variant of concern.” Delta, for example, represents more than 95% of the coronavirus cases SoRelle is tracking.

“At that point, there are enough cases that we can start looking to see if there are other characteristics, either how it impacts vaccine efficacy or hospitalization rates or mortality in a hospital to then see if it should be more concerning.”

How COVID Variants Have Spread In North Texas Throughout 2021

The first coronavirus variant, alpha, arrived in North Texas at the end of January. It took about three months to become the most prevalent strain. When delta showed up at the end of May, SoRelle said things started to move quickly.

“At first, we were looking just twice a day during June. Then the number of positives listed got longer and longer. I had to check it more and more times. By the beginning of July, [delta] was the predominant variant,” SoRelle said. “Alpha was almost entirely gone at that point. Just over very quickly, which is very surprising.”

He said while there are other variants across the globe, delta is outcompeting most of them.

“Delta variant is just so much more infectious than many other variants out there,” SoRelle said. “It's hard for them to get a foothold.”

Emerging Variants In North Texas

SoRelle said he and others at UT Southwestern Medical Center are tracking a variant out of South America called lambda, of which there’s been a few cases so far in Dallas County.

He mentioned he’s also monitoring a mutation of delta known as “delta plus.” It has a mutation in the spike protein of the virus, but SoRelle said the lab has only found one sample of the variant mutation among hundreds of delta specimens.

He’s also guessing this won’t be the end of new variants.

“We've seen five or six different ones this year alone, just the first half of the year,” SoRelle said. “It seems entirely likely that if we continue on the same trajectory, that we'll continue to see more variants.”

SoRelle said the best way to slow the virus is for more people to get the vaccine.

“If you want to stop all these variants from continuing to appear and keep hearing about them, the best way to stop it is to get vaccinated,” SoRelle said.

Got a tip? Email Elena Rivera at You can follow Elena on Twitter @elenaiswriting.

KERA News is made possible through the generosity of our members. If you find this reporting valuable, consider making a tax-deductible gift today. Thank you.

Elena Rivera is the health reporter at KERA. Before moving to Dallas, Elena covered health in Southern Colorado for KRCC and Colorado Public Radio. Her stories covered pandemic mental health support, rural community health access issues and vaccine equity across the region.