April 21, 2020

'We sacrificed quality for speed': Why rapid antibody tests may not be the key to reopening the US

Daily Briefing

    Policymakers and U.S. health officials are looking to expand antibody testing for the new coronavirus as a way to provide key data that could allow them to reopen businesses and ease social distancing measures—but some experts warn that many of the tests are unregulated and often produce unreliable results.

    Your Covid-19 checklist to expand capacity

    States, businesses see mass antibody testing as key to ramping up operations

    Multiple states and some businesses over the past few weeks have started to roll out mass antibody testing for the new coronavirus as part of their strategies for determining whether it's safe to allow essential employees to work, reopen nonessential businesses, and ease social distancing measures intended to curb the virus' spread.

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    Manufacturers of the antibody blood tests say they can determine whether an individual already contracted the new coronavirus based on the presence of antibodies in their blood—even if they didn't experience symptoms of Covid-19, the disease caused by the virus. The majority of antibody tests currently available in the United States are rapid tests, which manufacturers claim can identify coronavirus antibodies within minutes.

    Public health and government officials have argued that widespread antibody testing is key to safely reopening nonessential businesses and scaling back social distancing measure across the country. President Trump on Friday said the tests could be used to show "who might have developed the wonderful, beautiful immunity" to the new coronavirus, though public health experts have warned that it's still unclear whether having coronavirus antibodies means a person has developed any immunity to the virus.

    Still, states, localities, and some businesses have embraced rapid antibody tests as a tool to inform their plans for reopening businesses and scaling back social distancing restrictions.

    For instance, New York Gov. Andrew Cuomo (D) on Sunday announced the state would begin mass antibody testing on a random sample of residents, starting with an initial rollout of 2,000 antibody tests per day. Cuomo said the testing could give officials "the first true snapshot of what we're really dealing with" in terms of how many New York residents have been exposed to the new coronavirus. He added, "Any plan that is going to start to reopen the economy has to be based on data and that means it has to be based on testing."

    A similar effort is underway in Laredo, Texas, the New York Times reports. In Chicago, officials have employed the tests to detect infection rates among the city's homeless population and are considering expanding the effort to test nursing home residents, according to Allison Arwady, commissioner of the city's Public Health Department.

    Some health systems and other businesses are launching widespread antibody testing initiatives, as well. For example, Beaumont Health in Michigan plans to offer voluntary antibody testing to all of the system's 38,000 employees and thousands of affiliates, the Times reports. Separately, the clinical labs network Eurofins is working with subsidiary Boston Heart Diagnostics to test workers at 100 hospitals, according to the Times.

    Are antibody tests reliable?

    But health experts are raising concerns about the testing rollouts, noting that a vast majority of the tests currently available in the United States haven't been approved by FDA. Further, experts say early data suggests some of the tests are highly unreliable and, in some instances, providers may be using the tests inappropriately.

    The Times reports that, to increase testing capacity in the country, FDA loosened regulations regarding diagnostic and antibody tests for Covid-19, and many such tests can now be sold in the United States without first receiving the agency's formal review or approval. Since March, FDA has allowed manufacturers to sell their tests as long as they validate their own results and notify the agency of the outcomes, the Times reports. Under the relaxed regulations, more than 90 companies selling antibody tests for the new coronavirus have entered the U.S. market without traditional government vetting.

    Health experts warn that some of those antibody tests may not be high quality, even though manufactures claim they are. "It's a real mess," said Michael Osterholm, an infectious disease expert at the University of Minnesota. "This is the wild, wild West in terms of testing, and at a time when we need real definition of what these tests mean."

    For instance, after health officials in Laredo administered 20,000 antibody tests to residents, the local health department found the tests had a reliability rate of about 20%—far lower than the 93% to 97% reliability rate the manufacturer had advertised. A police investigation eventually led the federal government to seize the remaining tests, the Times reports.

    Rapid antibody tests, which are the most commonly used antibody tests in the United States right now, are proving to be the most unreliable, according to the World Health Organization (WHO).

    For example, Britain found that millions of rapid tests it acquired from China were not sensitive enough to detect coronavirus antibodies in severely ill patients, the Times reports. Similarly, officials in Spain last month learned that an initial batch of rapid testing kits had an accuracy rate of 30%, rather than 80% accuracy rate the manufacturer had advertised, according to the Times.

    Giorgio Palù, a microbiologist and former president of the European Society for Virology, explained that rapid antibody tests are particularly problematic because "they do not have the required sensitivity and specificity."

    As Osterholm said, "We sacrificed quality for speed."

    Even antibody tests that have gotten FDA's approval could present challenges when it comes to estimating accurate infection rates, the Times reports.

    According to the Times, Cellex's FDA-authorized antibody test has a false-positive rate of about 5%. According to Osterholm, that means that, in a community where 5% of the population has been infected with the new coronavirus, the test could result in as many false-positive results as accurate results.

    Further complicating the matter is unclear guidance from FDA that's led to some health care providers using the tests improperly, the Times reports. According to the Times, FDA in a guidance document has said antibody tests could be performed in "point-of-care" settings, which include doctors and nurses' offices. However, FDA in the guidance also said antibody tests that haven't gotten the agency's approval must be conducted in high-complexity laboratories.

    So far, FDA has approved just four antibody tests for the new coronavirus, which were developed by Cellex, Chembio Diagnostic Systems, Mount Sinai Laboratory, and Ortho Clinical Diagnostics. However, other companies have inappropriately claimed that their tests were approved by FDA, and providers in some instance have administered antibody tests that they were not authorized to use under FDA's guidance.

    How should the tests be used?

    Given the uncertainties about the tests' accuracy and persisting unknowns regarding whether a person who has antibodies to the new coronavirus is immune to future infection, experts say officials shouldn't rely on antibody tests alone to inform their strategies for easing social distancing restrictions and reopening businesses.

    "We're really far from that," Osterholm said, adding, "We're not even in the second inning of a nine-inning game at this point."

    Ida Bergstrom, a physician in Washington, said officials should consider rapid antibody tests as only "one tool" to assess the spread and impact of the new coronavirus on their communities, and Syed Ashraf, a physician in Virginia, said positive antibody test results shouldn't be viewed as "a free license [for patients] to run around and do whatever [they] feel like."

    Osterholm said, "[I]n the end, when it's people's lives that are hanging in the balance, safety has to take precedence over speed" (Eder, New York Times, 4/19; Owens, "Vitals," Axios, 4/20; Young, Politico, 4/19).

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