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FDA warns COVID-19 test could produce false negatives. It's used at 100+ sites in California

Nicole Hayden
Palm Springs Desert Sun

More than a hundred COVID-19 testing sites throughout California could be producing a substantial number of false-negative results, according to the U.S. Food and Drug Administration. 

The FDA released a statement this week alerting patients and health care providers to the risk of false results with a particular type of SARS-Cov-2 test from Curative, a California startup medical testing company founded in 2020.

According to Curative's website, it has more than 100 testing sites scattered throughout California, including large clusters in the Inland Empire, Bay Area and Los Angeles County. Some of those sites are in partnership with local counties.

The warning comes as California copes with its worst surge of the pandemic and some of the highest levels of COVID-19 in the country. Hospitals in Los Angeles and across the southern half of the state are overwhelmed with patients, oxygen used for treatment is running low and ambulances sometimes wait hours to unload patients.

As the Curative tests are self-administered, there is a chance of the swab not being conducted properly, leading to inaccurate results, according to the FDA.

Curative test specialist Troy Roberts gives a motorist a self-administered COVID-19 test kit outside the La Quinta Wellness Center in La Quinta, Calif., on December 30, 2020.

A false-negative test could mean individuals do not self-isolate, leading to increased spread of the virus within the community.

Curative issued a statement this week defending its test: "Curative'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 FDA reiterated in the safety communication,'' the company said.

Company officials said they remain committed to following all federal regulations and to ensuring their tests "meet or exceed our customers' expectations.''

The FDA offered no information on what triggered the warning Monday, but it appeared to be about the test's accuracy for people who don't exhibit symptoms of COVID-19, such as fever, sore throat and fatigue.

Riverside County: No need to re-test unless you fall under 2 exceptions

In Riverside County, all four county testing sites are run by Curative, which includes locations in Indio, Perris, Riverside and Lake Elsinore. However, the county does not incur any costs from the partnership, according to spokesperson Jose Arballo Jr.

"Self-administered tests, regardless of the vendor, have more potential to create false negative results compared to tests administered by a health professional," Riverside County Health Officer Dr. Cameron Kaiser said in a statement. "This is because sometimes people don’t follow the instructions precisely, even though they intend to do so. If there isn’t enough of viral material in the sample for any reason, it won’t be positive."

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While there is a chance for false-negative results from the test, Kaiser said any positive COVID-19 test results from a Curative self-administered test are "almost always correct" and individuals should act accordingly by isolating and monitoring their symptoms. 

Kaiser said he doesn't recommend everyone who received negative results from a Curative test immediately get re-tested. However, if someone you came in contact with tested positive and you did not, Kaiser recommends a re-test. The same advice goes if you tested negative but are now experiencing symptoms.

Los Angeles stands by tests, Congress will find alternative

The nation’s second-largest city said it will keep using the coronavirus test while Congress, which has used the same test, is seeking an alternative.

Los Angeles Mayor Eric Garcetti, who embraced Curative and opened testing to everyone last spring when tests were in short supply elsewhere, stood by the company Thursday. He said a third of all positive test results in the city have been in people without symptoms.

“That’s 92,000 people who otherwise might not have known, might have been spreading,” he said. "That has helped us predict those surges in hospitalizations and deaths as a result. To me that proof is in the pudding.”

The self-administered Curative test was also used to screen staff on Capitol Hill since at least November. Admiral Brett Giroir, the Trump administration’s top testing official, said Thursday that his Department of Health and Human Services is working with the office of the congressional physician to find an alternative test for use on Capitol Hill.

Dr. Clemens Hong, who oversees coronavirus testing for Los Angeles County, said the company’s initial emergency use authorization from the FDA was based on a limited study of subjects with coronavirus symptoms. The company later performed a clinical study involving asymptomatic subjects but the FDA balked at approving use for people without symptoms.

“They actually feel that those data don’t support the use of the (test) in asymptomatic individuals and there’s a little bit of a disagreement between Curative and the FDA,” Hong said.

Further north, Sonoma County announced a partnership with Curative Dec. 22, as did Marin County in early January. The city of Riverside did so Nov. 10, among many others.

What is Curative?

Curative was founded just a year ago by British wunderkind, Fred Turner, then 25, who was making sepsis tests and pivoted to the coronavirus when the pandemic struck. He developed an easy-to-use method that collected a specimen by swabbing the inside of the mouth after coughing.

The test didn't require the nasal swabs that were in short supply and had created a bottleneck at a time when more testing for COVID-19 was desperately needed.

The company's test was given emergency use authorization by FDA and was one of the few approved at the time that relied mainly on saliva or oral fluids.

Curative tests are also used in Chicago and Houston.The Houston Health Department, which only helps Curative locate and promote its test sites in the city, was not planning to end its partnership with the company, said spokesman Scott Packard. The department noted that the FDA did not recommend discontinuing the tests and said all tests are susceptible to false results.

The FDA in its warning said that to reduce the risk of false-negative results, the Curative tests should be performed according to their instructions, which state that it is for use in people displaying symptoms of COVID-19.

Despite such instructions, top federal health officials have given their blessing to use many FDA-cleared tests to screen people without symptoms, in an effort to slow the silent spread of the disease. Experts estimate anywhere between 40% to 60% of people infected do not show any symptoms, despite carrying similar levels of the virus as those with full-blown COVID-19 illness.

Giroir, the Trump administration’s top testing official, stressed that the test should only be used according to its FDA-authorized label.

“We are always open to new data from Curative to show it can be effective in other situations, but right now my colleagues at the FDA have made the conclusion that it needs to be used on-label,” said Giroir.

The FDA has previously flagged accuracy concerns with several other COVID-19 tests, including a rapid test that was frequently used at the White House last year. The agency generally discloses few details as it investigates accuracy.

Suzanne Sandmeyer, a professor of biological chemistry at the University of California, Irvine, questioned why the FDA had issued such a warning without more information that could be useful to the public.

“It’s disappointing they couldn’t be more specific because it might be discouraging for people who might be planning to be tested, especially if it’s the major test in LA right now,” Sandmeyer said.

Hong wouldn’t discuss the data he had seen but said the percentage of false negatives was very small and would not lead the county to immediately stop using the test. He wasn’t concerned that bad test results were leading to the exponential spread of the virus in the county. 

“When you have as much infection as we do in LA County, ... the risk of encountering someone in the community that is positive is really high,” he said. “That’s what’s causing the spread. It isn’t the rare false negative or an occasional false negative test.”

Associated Press and City News Service contributed to this report. Desert Sun reporter Nicole Hayden covers health in California. She can be reached at Nicole.Hayden@desertsun.com or (760) 778-4623. Follow her on Twitter @Nicole_A_Hayden.