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


When fans of the group Phish started falling ill with Covid-19 across the country after a Halloween concert weekend in Las Vegas, public health officials were largely unaware of what seems to have been a super-broadcaster event. In one Facebook post mid-November with hundreds of responses, onlookers compared symptoms and positive test results, many of which came from tests done at home. But that data has not been added to the public health counts of the spread of Covid.

It’s a story that is becoming common in the era of rapid home Covid testing: People who test positive are almost never counted by public health agencies tasked with bringing the pandemic to a halt. While home testing has distinct advantages – it is convenient and quickly informs people of their infection status so they can take action to avoid spreading the virus – most people who test positive go unreported. to health officials unless they are sick enough to see a doctor.

Certainly, the increasing availability of home testing is good news for a country that has gone through more than a year of a pandemic with inadequate testing resources. Yet, as the United States enters a second pandemic holiday season with the Omicron variant looming, state and local health departments increasingly rely on incomplete data and educated guesses to capture the highs and the lows of the infection rate and to guide decision-making. Home test samples, for example, are not 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.


“If no one reports 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 of ​​the true positivity rate.”

Grover and his colleagues have spent months tracking the availability and use of Covid tests in the United States and have grown increasingly concerned about the data black hole that is home antigen testing, particularly with cases on the rise again. The Biden administration last week announced plans to make home testing free and dramatically increase testing availability. While these tests may still be difficult to set up, the Food and Drug Administration has granted emergency use authorizations for 10 home tests for sale to consumers, and more are online, so the tests at homes are poised to become the primary Covid tracker.


To complicate matters, health agencies have no idea how many home tests are done in their states and communities, and therefore how many results they are missing. The indications are that home testing nationwide has already exceeded the number of PCR tests – which are processed by laboratories which are required to report the results to health agencies. In contrast, most home tests have no mechanism for patients to easily report their results. Only two of the approved home tests include an app to report the results, and it’s not clear if these are used in most states. Most people are too busy to care, too, and the Centers for Disease Control last month abandoned guiding urging home test users to report results to public health agencies.

Mara Aspinall, Managing Director of Health Catalysts Group, an Arizona-based consulting firm that focuses on life science companies, tracked test data using industry reports, production numbers test and many other sources. It is almost impossible to get an accurate reading of the exact number of home tests used in the United States each week, but its best estimates show that home tests now represent the majority of Covid tests and the number will increase as more new tests will be available. Aspinall says by his tally, around 40 million Covid tests are done each week. Of these, she estimates, 12 million are PCR tests and about 28 million are antigen tests. Of the antigen tests, the vast majority are done at home and never get reported to public health agencies, she said.

The volume of home testing and the growing lack of information is driving a shift towards managing the pandemic through personal behavior, leaving public health officials dependent on people’s personal choices.

“Why are we testing at all? We are testing not to count the number. We’re testing so that we can give people the information they need to isolate the positives, ”Aspinall said. “It would be much better if we knew precisely, reliably and consistently how the tests are performed. But the most important problem is that people use the tests and use them effectively and regularly. “

STAT contacted public health agencies in 10 states currently experiencing an increase in Covid cases and found that none were able to track data regarding home tests. State officials have said they are confident in their Covid data and have played down the impact of the home test data gap, at least so far. They said they were using a patchwork of PCR test data, estimates, self-reports and, in some places, sewage sampling to detect infection levels in their communities and guide policy. health.

In New York, state health officials are strongly promoting a message for those who test positive, at home or in a doctor’s office, to follow Covid protocols that include isolation and quarantine. But in many other states, this focus has faded from public attention as political and popular will wears out.

In Massachusetts, residents are urged to confirm rapid antigenic test results with a PCR test, drawing on hundreds of free testing sites across the state. But in less funded, more rural, and Republican-led parts of the country like Montana, large-scale on-demand PCR testing just doesn’t exist.

Public health agencies are quick to point out that home testing is a key weapon in the arsenal against Covid.

“We believe that continuing to make testing available – both supervised and unmonitored – is valuable for several reasons,” said Alicia Shoults, spokeswoman for the Ohio Department of Public Health, in an email. .

“As more people test and report their results, it gives us a better (though admittedly imperfect) idea of ​​our overall case rates. And even when people don’t report, they use their test results to inform their behavior about going to school or work, going to visit relatives. These tests can therefore help slow the spread of the community and protect vulnerable residents. “

Grover said a solution could be as simple as adding a barcode to home test kits that link to a website or app that allows users to scan or call and report the results. . Michael Mina, a former Harvard epidemiologist and strong advocate for home Covid testing, recently joined a biotech software company, eMed, in part to address the data breach issue, he told the Boston Globe. The company is working with a home testing company on a test that would relay the results to local health agencies and come with a postage-paid envelope allowing consumers to submit positive swab samples for sequencing.

Grover called for a national solution, adding that as with anything related to the pandemic, communities of color will most likely be affected by inaccurate surge monitoring. “The federal government needs to take the lead because this is a patchwork of not just inequalities but bad public health policies,” he said.

This story is part of a project funded by the NIHCM Foundation. The foundation played no role in the writing, editing or presentation of this work.