The coronavirus test provided daily to tens of thousands of residents in Los Angeles and other parts of California may be producing inaccurate results, according to a warning from federal officials that may raise questions about the accuracy of the infection data that shapes the response to pandemic.
The Food and Drug Administration guidance warns healthcare professionals and patients that testing by Curative, a one-year Silicon Valley start-up that provides oral smear tests at the 10 drive-through test sites in Los Angeles , carries a “risk of false results, particularly false negative results. ”
To reduce the risk of false negatives, the curative test should only be used on “symptomatic individuals within 14 days of the onset of COVID-19 symptoms” and the smear should be observed and directed by a healthcare professional, said the FDA.
The guidance, issued on Monday, repeats the instructions that the FDA issued when the test was first granted an emergency use authorization.
The FDA warning appears to strongly contradict Los Angeles Mayor Eric Garcetti, who in April made the coronavirus test available to anyone, regardless of symptoms. In August, Garcetti said he disagreed with the Centers for Disease Control and Prevention’s guidance that the tests should be administered only to symptomatic patients.
Conflicting approaches raise new questions about the accuracy of the city’s reported COVID-19 positivity rates, including whether false negatives have given people the mistaken assumption that they could ignore public health guidelines and meet with others outside their residences, contributing to a record level of community propagation.
Curative, founded by a 25-year-old British businessman, has administered more than 11 million tests across the country, including in other major cities like Chicago, San Francisco, Houston, Atlanta, Miami and Seattle. The company maintains a $ 42 million contract to conduct tests at U.S. military treatment facilities and also test members of Congress, including those who have no symptoms.
Unlike nasal smear tests, which must be administered by a medical professional deep in the patient’s nose, the Curative test is an oral smear that can be self-administered. Patients are required to cough three times, spit in the mouth and then rub a cotton swab around the gums, cheeks and tongue.
The Times reported in April that while the Curative process is much more comfortable than that of nasal swab tests and makes the tests much more widely available, it is not the method recommended by the FDA and may be less accurate.
Los Angeles County stopped Curative’s oral smear test at its test sites in June. Public health director Barbara Ferrer said at the time that nasal tests produced fewer false negatives.
Dr. Clemens Hong, who oversees coronavirus testing for LA County, said in an email that the county is aware of FDA guidelines and is “reviewing and evaluating the results of clinical studies”. According to him, any type of oral smear test is at risk of false negatives, as the results depend on the correct collection of the saliva sample and the viral load it contains.
Curative still processes a “limited number” of tests on pop-up test sites that are supported by the county, said Hong.
The city continues to administer the Curative oral smear test at 10 drive-through and walk-up test sites, including a huge facility at Dodger Stadium that processes thousands of tests per day.
When the county stopped using curative testing, Garcetti spokesman Alex Comisar said Los Angeles was “confident in the curative test kits and lab work”.
Since the end of March, more than 3.37 million coronavirus tests have been administered at test sites in the city since the start of the pandemic, according to city data. Many of these tests were processed by Curative.
A representative from Curative said in a statement that the company’s test “has been validated and is being offered during the pandemic under an Emergency Use Authorization and is labeled with specific warnings, precautions and limitations that the FDA reiterated in the Safety Communication. Test performance and labeling, however, did not change, nor did the company observe any changes in test performance. “
The Curative study conducted to validate its test excluded patients who were asymptomatic, and the company told the FDA, in its request for emergency clearance, that the test is “limited to patients with symptoms of COVID-19”.
When the FDA issued an emergency authorization for the Curative test in April, it specifically authorized testing for samples “of individuals suspected of COVID-19 by their health care provider”.
The FDA guidance warned that the curative test must be “directly observed and directed during the sample collection process by a trained health professional at the sample collection site.”
At Dodger Stadium, patients administer the test themselves in their cars. A video showing the correct method of administering the swab is played on huge screens at the test site, and the bag containing the test supplies – which is delivered through the car window – also contains instructions.
Curative is one of dozens of companies that have accelerated coronavirus testing and obtained emergency clearance from the FDA after the agency announced in late February that it was removing regulatory hurdles.
Companies with emergency clearance cannot promote their tests as “safe or effective” for virus detection. The policy prevents companies from having to meet approval guidelines that can take up to two years.
Times staff writers, Soumya Karlamangla and Melody Peterson, contributed to this report.