Growing use of home Covid-19 tests leaves health agencies in the dark about unreported cases



When fans of the band Phish started falling ill with Covid-19 all over the country after a Halloween concert weekend in Las Vegas, public health officials were largely in the dark about what appears to have been a superspreader event. In a Facebook post from mid-November with hundreds of responses, concertgoers compared symptoms and positive test results, many of those from tests taken at home. But those data weren’t added to state public health tallies of Covid’s spread.
It’s a story that’s becoming commonplace in the era of rapid home Covid testing: People who test positive are almost never counted by public health agencies charged with bringing the pandemic to heel. While home tests have distinct advantages — they’re convenient and quickly inform people of their infection status so they can take steps to avoid spread the virus — most who test positive don’t come to the attention of health officials unless they are sick enough to see a doctor.
To be sure, the growing availability of home tests is good news for a country that stumbled through more than a year of the pandemic with inadequate testing resources. Still, as the U.S. moves into a second pandemic holiday season with the Omicron variant looming, state and local health departments are increasingly relying on incomplete data and educated guesses to capture ups and downs in the infection rate and to guide decision-making. Home-testing samples, for example, aren’t submitted for genomic sequencing, which could delay identification of the Omicron variant in communities. And contact tracers can’t trace cases they don’t know about.
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“If nobody’s reporting the tests, are we really getting the information we need?” said Atul Grover, health policy researcher and executive director of the Association of American Medical Colleges. “We have no idea what the true positivity rate is.”
Grover and his colleagues have spent months tracking Covid testing availability and usage in the United States and have grown increasingly worried about the data black hole that is home antigen testing, particularly with cases again on the upswing. The Biden administration last week announced plans to make home testing free, and widely increase testing availability. While these tests can still be difficult to get in places, the Food and Drug Administration has given emergency use authorizations to 10 home tests for sale to consumers, and more are coming on line, so home testing is poised to become the primary Covid tracker.
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Complicating matters is that health agencies have little idea how many home tests are performed in their states and communities, and thus how many results they’re missing. Indications are that home testing nationally has already surpassed the number of PCR tests — which are processed by labs that are required to report results to health agencies. In contrast, most of the home tests have no mechanism to enable patients to easily report their results. Only two of the approved home tests include an app to report results, and it’s unclear whether those are used in most states. Most people are also too busy to bother, and the Centers for Disease Control last month dropped guidance urging users of home tests to report results to public health agencies.

Mara Aspinall, managing director of Health Catalysts Group, an Arizona-based consulting company that focuses on life sciences firms, has been tracking testing data using industry reports, test production numbers, and a host of other sources. It’s nearly impossible to get a precise read on exactly how many home tests are used in the U.S. each week, but her best estimates show that home testing now accounts for the majority of Covid testing and the number will grow as more tests become available. Aspinall says by her tally, roughly 40 million Covid tests are performed each week. Of those, she estimates, 12 million are PCR tests and roughly 28 million are antigen tests. Among the antigen tests, the vast majority are taken at home and never reported to public health agencies, she said.
The volume of home testing, and growing information gap, is bringing about a shift toward managing the pandemic through personal behavior, leaving public health officials reliant on people’s own personal choices.
“Why do we test at all? We test not to count the number. We test to be able to give people the information to isolate the positives,” said Aspinall. “It would be much better if we knew in an accurate, reliable and consistent way, how may tests are being done. But the most important issue is that people use the tests and use them effectively and regularly.”

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STAT contacted public health agencies in 10 states now experiencing rising Covid cases and found none was able to track the data around home testing. Officials in the states said they are confident in their Covid data and minimized the impact of the home test data gap, at least so far. They said they’re using a patchwork of PCR test data, estimates, some self-reporting, and in some places, wastewater sampling to detect infection levels in their communities and guide health policy.
In New York, state health officials are heavily promoting a message for those who test positive, at home or in a doctor’s office, to follow Covid protocols that include isolating and quarantine. But in many other states, that guidance has faded from public attention as political and popular will tires.
In Massachusetts, residents are urged to confirm rapid antigen test results with a PCR test, relying on hundreds of free test locations across the state. But in less-funded, more rural and Republican-led parts of the country such as Montana, widespread PCR testing on-demand simply doesn’t exist.
Public health agencies are quick to point out that at-home tests are a key weapon in the arsenal against Covid.

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“We believe that continuing to make testing available — both proctored and unproctored — is valuable for multiple reasons,” Alicia Shoults, spokesperson for the Ohio Department of Public Health, said in an email.
“To the extent more people are testing and reporting their results, it gives us a better (though admittedly imperfect) sense of our overall case rates. And even when people don’t report, they are using their test results to inform their behavior regarding going to school or work, going to visit relatives. So these tests can help slow community spread and protect vulnerable residents.”
Grover said one solution could be as simple as adding a bar code to home testing kits that links to a website or app that allows users to scan or call and report results. Michael Mina, a former Harvard epidemiologist and vocal advocate of home Covid testing, recently joined a biotech software company, eMed, in part to solve the data reporting problem, he told the Boston Globe.  The firm is working with a home testing company on a test that would relay results to local health agencies and come with a postage-paid envelope for consumers to submit positive swab samples for sequencing.
Grover called for a national solution, adding that as with all things related to the pandemic, communities of color will be most likely harmed by inaccurate surveillance of surges. “The federal government needs to take a lead, because it is such a patchwork not only of inequality but of bad public health policy,” he said.
This story is part of a project funded by the NIHCM Foundation. The foundation played no role in the reporting, editing, or presentation of this work.



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