Why Thousands Of Antigen Tests Are Left Out Of Texas COVID-19 Tally

Aug 4, 2020

From Texas Standard:

On Aug. 3, Texas reported 5,839 new COVID-19 cases. But that doesn't mean all positive cases are reflected in the state's tally.

The Texas Department of State Health Services is not reporting antigen tests – the rapid COVID-19 tests that are often done in doctors' offices or clinics that are much faster than the more common PCR tests that require a long swab inserted into a patient's nose. Matt Dempsey, data editor for the Houston Chronicle, and his colleagues recently investigated the undercounting of antigen tests by Texas state health authorities.

Antigen tests have had a reputation for being less reliable than PCR tests. The worry is that they will give a patient a false-negative result, meaning they will have the new coronavirus and the test won't detect it. But more and more people are using them. Two antigen tests are approved by the U.S. Food and Drug Administration.

"People want to know whether they're infected, and they want to know now," Dempsey said.

Out of Texas' 254 counties, 11 are reporting positive antigen tests. But those results often don't make it to state officials. That's partly because of a backlog of test results the state receives by fax – an old-fashioned mode of communication Dempsey said the state believes is more secure for sending medical information. Also, Dempsey said Texas still considers positive antigen tests "probable" COVID-19 cases – not confirmed cases, because the test looks for active coronavirus infection in the body, not for the existence of new coronavirus DNA.

The undercount is also because some counties, like Montgomery near Houston, are simply not sending their antigen results to state health authorities.

"They are tracking their antigens, but they're not sending that data to the state became they were under the assumption that the state wasn't interested in it," Dempsey said.

Antigen testing in Texas is only going to grow. It's already being used in nursing homes where outbreaks of COVID-19 have been severe. Now, Dempsey said the federal government is sending "thousands of antigen tests" to nursing homes nationwide, including to over 20 facilities in Texas.

"As the popularity of the test increases, it means we're going to have less of [an] ability to have a complete surveillance of how the virus is hitting Texas."

Web story by Caroline Covington.

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