COVID-19 widespread testing is crucial to fighting the pandemic, but is there enough testing? The answer is in the positivity rates.
Even as advocates cite bureaucratic red tape blocking fast and cheap home coronavirus tests, the federal government’s regulatory agency overseeing testing says it will be flexible and encourage developers to seek approval.
The Food and Drug Administration issued a document on July 29 calling for home tests to correctly identify the virus at least 90% of the time. But a high-ranking FDA official overseeing testing told USA TODAY the agency will consider tests with lower sensitivity.
Jeffrey Shuren, director of the FDA’s Center for Devices and Radiological Health, said the agency’s recommendations issued more than two months ago are “starting points.”
“Our door has been open, and we’re very flexible because we’re trying to do all we can, at least from an FDA side, to have test availability in the country,” Shuren said. “We’ve been taking essentially all comers.”
Advocates say rapid and cheap home tests might be as important as a vaccine in the fight against COVID-19, even though the tests are less accurate than lab-based PCR tests that cost $100 or more. The nation has never attempted such widespread screening of people who have no symptoms, and the outbreak among those in President Donald Trump’s orbit shows how the virus can spread even before the best tests can detect it.
No test developer has filed paperwork with the FDA seeking authorization for home use of these rapid tests, but several companies are conducting studies and plan to do so.FDA approval would allow them to sell millions of such coronavirus tests directly to consumers without a doctor’s referral.
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Quidel, Becton, Dickinson and LumiraDx already have gained FDA authorization to sell antigen testing instruments that provide quick results to labs or clinics. Abbott Laboratories is marketing a $5 rapid, portable test administered by a health care professional. The federal government has purchased 150 million of these “lateral flow” tests, which provide results within 15 minutes.
Abbott Laboratories’ BinaxNOW rapid COVID-19 nasal swab test. (Photo: AP)
Testing companies developingrapid home tests and their allies want the FDA and other federal agencies to loosen restrictions on home tests and ease authorization.
Dr. Michael Mina, a Harvard epidemiologist who has been advocating for such cheap tests since June, says some testing companies have been discouraged by the agency’s initial recommendations.
“In some ways, the language that the FDA has used has actually caused the companies not to go forward with these types of tests for public health,” Mina said.
In a New England Journal of Medicine perspective posted Sept. 30, Mina and two co-authors argued evaluating tests based on sensitivity alone “neglects the context of how the test is being used.”
PCR tests analyzed at labs have greater sensitivity and detect the virus’s genetic material at even low levels. Positive lab tests might occur in the beginning or tail end of an infection when someone is less likely to spread the coronavirus to others.
Mina and his co-authors, Daniel B. Larremore and Roy Parker, both of the University of Colorado, wrote that inexpensive antigen tests used frequently are more likely to detect when a person is infectious. Frequent testing can alert people when they are infectious so they can take precautions and prevent further spread.
“Frequent use of cheap, simple, rapid tests will accomplish that aim, even if their analytic sensitivities are vastly inferior to those of benchmark tests,” the authors wrote. “Such a regimen can help us stop Covid in its track.”
FDA officials said the agency would consider authorizing a home test below the 90% sensitivity threshold if packaged as multiple tests. For example, a test that is 70% sensitive might not be desirable as a one-time test, but multiple tests could bolster overall accuracy.
“You may want to consider a serial testing strategy,” the FDA’s Shuren told USA TODAY. “Maybe you’re going to co-package two tests, where you take one test one day, and take another the next day or maybe two days after. That’s going to increase your hit rate.”
Mina acknowledges that the FDA has been open to feedback from test developers, but he says some companies have been reluctant to apply for home testing for fear they won’t meet the agency’s standards.
He said he first viewed Cambridge, Massachusetts-based E25Bio rapid test in April. It wasn’t accurate enough to be a diagnostic test at the time, and the company has been working to refine the test. The company already has applied to market its rapid antigen test as a diagnostic that can be used at labs, but it has yet to seek approval for its long-term goal of an inexpensive home test.
“They’ve spent a lot of time trying to improve it,” Mina said. “So unfortunately … the price will go up.”
Other companies developing home tests said they are conducting clinical studies to demonstrate their products can work.
Cellex’s rapid antigen test has demonstrated nearly 90% sensitivity. The test uses lateral flow technology, similar to a pregnancy test, that displays results users can see. Cellex’s partner, Gauss, uses a smartphone app with computerized vision technology to confirm results and facilitate reporting cases to public health agencies.
The companies expect to complete clinical studies in about one month, a Cellex spokesman said.
Gauss Founder and CEO Siddarth Satish said the technology component aims to help consumers to accurately read results, particularly when low antigen levels can make lines appear faint.
“Optimizing for accuracy and precision is absolutely critical,” Satish said.
‘Huge public health problem’
The FDA had made a concession in another critical area: reporting.
If consumers buy their own tests, there’s no guarantee they will report results to local or state public health authorities.
Labs are required to report coronavirus results to public health agencies under the federal CARES Act, although public reporting through official channels still has holes. Many states don’t track the results from antigen tests that are given at doctors’ offices, urgent care centers or nursing homes. There would be even less ability to track results from home tests.
“Reporting is going to be a huge public health problem,” said Eric Blank, the Association of Public Health Laboratories chief program officer.
States and local health departments track and report test results to the Centers for Disease Control and Prevention to monitor trends and spur action. The public reporting also allows public health workers to trace the contacts of infected people to curb spread.
Blank said even antigen tests administered at a workplace, a university or a school usually involve a nurse or other official who takes charge of reporting. For individuals, there might be little motivation to share results.
“Compliance has been a big issue throughout this (pandemic),” Blank said, citing people who refuse to use masks as an example.
The FDA knows test manufacturers have no carrot or stick to compel someone to report results from a home test.
“All we’re really saying when we put our recommendations in, is that you should think about facilitating reporting,” Shuren said. “We’re not requiring you to do anything, but you should think about it.”
Ken Alltucker is on Twitter as @kalltucker or can be emailed at firstname.lastname@example.org
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