June 10, 2020

Why it's so hard to test for the new coronavirus at home

Daily Briefing

    As the demand for testing for the new coronavirus increases, companies are rolling out new at-home tests to detect both current infections and antibodies to the virus. However, health experts are worried that a nationwide rollout of the new tests could be weakened by high costs, inaccuracies, and a lack of government surveillance.

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    Compared with other countries, the United States has a low per-capita testing rate for the novel coronavirus. According to Vox, supply shortages have caused diagnostic tests for the virus to become scarce in some places around the country.

    Even where diagnostic tests are available, processing the tests' results can take several days, and rapid tests for the new coronavirus, which claim to provide results within a few hours, are rarely available and often inaccurate.

    The lack of widespread testing "has crippled [the United States] from making more progress" on curbing the country's new coronavirus epidemic "and opening up the economy," according to Ryan Demmer from the division of epidemiology and community health at the University of Minnesota.

    Looking to capitalize off the increased need, companies over the past few months have flooded the U.S. market with more than 200 tests for the new coronavirus, and some are trying to speed up development of rapid, at-home diagnostic tests for the virus. The at-home, rapid tests would allow patients to collect their own samples for testing without having to visit a health care provider, either by using a nose and throat swab or by spitting into a test tube. And instead of sending the sample to a lab for processing, the patients would administer the test themselves and receive a result within an hour—similar to how an at-home pregnancy test works, Vox reports.

    Since late April, FDA has authorized six at-home testing kits for the new coronavirus, but those tests still require patients to send out their samples to a lab for processing. Further, only limited quantities of those tests are currently available.

    The downside of expanding rapid testing

    Health experts say rapid at-home tests could allow the government to perform large-scale, nationwide testing, which would help officials to better track the novel coronavirus's spread. However, they've also raised some concerns about the possibility of implementing widespread at-home testing.

    For example, some experts have said they're worried widespread at-home testing would make it difficult for officials to accurately track positive and negative test results. Currently, all diagnostic tests for the new coronavirus are processed at labs, which are required to report the tests' results to local health departments and the federal government. But if people begin performing the tests and receiving results at home, there's a chance they won't report the results to the proper authorities, Vox reports.

    That could harm efforts to curb the new coronavirus' spread, particularly when it comes to contact tracing. If a person who tests positive fails to report their results, their contacts may never be traced, Vox reports. Further, testing at home also could mean patients won't be in touch with a health care professional when they receive their results, and therefore a patient with positive results may not be notified to self-isolate—or they could end up stuck at home without access to health care, according to Vox.

    "If people were to do their own testing, ideally a procedure would be in place to ensure that the test results get reported to the local health department," said Amanda Castel, a doctor and professor of epidemiology at the Milken Institute School of Public Health at George Washington University

    Experts have also expressed concerns over the accuracy of the rapid, at-home tests.

    Demmer said any test administered on a large-scale would "have to be good and valid, and I think we're a long way from having those." He added, "If it's going to scale to millions and millions of people, it has to be very close to perfect, to really remove false negatives."

    And even if the tests are accurate, Alan Wells, a professor of pathology at the University of Pittsburgh and medical director at UPMC Clinical Laboratories, said the way the test is administered could impact the accuracy of their results. For instance, a nose-swab sample that is collected incorrectly could return a false-negative result, which could result in a patient going about life as usual even though they are infected with the new coronavirus and could transmit it to others.

    Castel said "[i]t would be important to" remind patients of the tests' limitations and "have a disclaimer to remind users that the test results only reflect someone's status for that particular day and time," so patients would know they must continue to practice caution regardless of their results.

    In addition, experts have said the costs of the tests could prove to be an obstacle to widespread use.

    Currently, FDA-authorized tests for the new coronavirus that allow patients to collect samples at home and send them to labs for processing cost around $135 to $150, which could prove to be unaffordable for both individuals and businesses that are looking to test large groups of employees.

    However, Vox reports that it's possible some rapid tests could be priced at less than $10 each, which would make them much more accessible.

    Even so, the United States likely is still months away from having its first rapid, at-home test for the new coronavirus on the market. David Walt, a professor of pathology at Brigham and Women's Hospital, said it could take between four and six months before one of the rapid tests receives FDA's authorization (Courage, Vox, 6/3; Scott, Wall Street Journal, 6/2; Aleccia/Barry-Jester, Kaiser Health News, 6/3).

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