Curative’s COVID-19 tests, including those done in Berkeley, could produce false negatives, FDA warns

The healthcare startup’s mouth swabs may be failing to show COVID infections, potentially leading to the spread of the virus in Oakland and Berkeley.

Covid-19 testing kiosk
Curative kiosk in Berkeley on Jan. 8, 2021. Photo: Pete Rosos

Mayor Jesse Arreguín is recommending that Berkeley residents avoid getting tested for COVID-19 at the Curative test site on San Pablo Avenue now that the FDA is raising questions about the accuracy of its results. But Alameda County health officials are less wary.

On Jan. 4, the Food and Drug Administration announced that Curative’s tests may be producing false-negative results.

“The U.S. Food and Drug Administration (FDA) is alerting patients and health care providers of the risk of false results, particularly false-negative results, with the Curative SARS-Cov-2 test,” the alert read. “Risks to a patient of a false negative result include: delayed or lack of supportive treatment, lack of monitoring of infected individuals and their household or other close contacts for symptoms resulting in increased risk of spread of COVID-19 within the community, or other unintended adverse events.”

The warning is prompting Berkeley officials to suggest that those looking to get tested look for operators other than Curative, at least for now.


“Obviously this new information is a concern, and we are looking into this, and we encourage residents to access other ways to get tested such as at the state-run Optum site run by LHI or through their health care providers,” Arreguín wrote in an email to Berkeleyside. (See info at bottom of story about some new testing options).

Berkeley has reached out to Curative and the state to get more information, said Matthai Chakko, the city spokesperson.

Curative, a healthcare startup founded in January 2020 to develop tests for sepsis, pivoted in early March to making COVID-19 tests and made promises that it would test millions of Americans. The company—which offers a less physically uncomfortable testing method, relying on a mouth swab instead of a deep nasal cavity swab—opened a free pop-up test site in Berkeley last July and another test site in Oakland in December. Curative still operates test sites in Oakland, Berkeley, San Francisco, San Mateo, Palo Alto and Los Angeles, and according to Politico, it has tested members of the U.S. Senate and House of Representatives.

Curative’s test was never FDA-approved, but the agency did authorize it for emergency use in April during the pandemic. But the FDA also pointed out in its alert that it had only authorized the Curative test for people who were exhibiting symptoms of the coronavirus, not those who were asymptomatic.

 “Collection of nasal swabs and oral fluid specimens is limited to symptomatic individuals within 14 days of COVID-19 symptom onset,” according to the FDA alert.

The Curative sites do currently offer tests to people without symptoms.

Academic studies have differed on whether oral-fluid tests like the one offered by Curative are as accurate as nasopharyngeal or NP tests, the one that uses a sample from inside a person’s nostrils.   

The FDA hasn’t made a similar announcement about false-negative tests since the pandemic began, according to its archive. The Centers for Disease Control and Prevention (CDC) removed its preference for a particular test last spring but has also acknowledged the false negative issue. In a patient fact sheet, the CDC warns that “it is possible for this test to give a negative result that is incorrect (false negative) in some people with COVID-19.”

Curative responded to the FDA’s announcement with a statement that they’re working with the agency to address its concerns.

The company’s CEO, Fred Turner, defended Curative’s testing method: “Regarding the FDA safety communication noting the risk of false results with the Curative SARS-CoV-2 test, we are confident in our data and we are working with the FDA closely on the matter. Testing sensitivity and accuracy on behalf of our patients is at the heart of our work,” he said.

The company also released a testimonial from Los Angeles Mayor Eric Garcetti, who said “he still trusts the Curative tests ‘deeply,'” according to the company.

It’s not immediately clear how many COVID-19 tests have been conducted by Curative in Oakland and Berkeley.

“We are aware of the FDA announcement regarding Curative COVID-19 testing,” the Alameda County Department of Public Health wrote in a statement to The Oaklandside today. “While the FDA’s announcement is concerning, we have no information to suggest these issues with Curative pose a wider threat to public health in Alameda County. For these reasons we are deferring to the FDA and their public announcement.”

In June, Curative’s CEO, Turner, told Bloomberg that his company was conducting roughly 25% of all tests in California. The company has maintained an average turnaround time of 36 hours. Curative operates three labs: one in Southern California, a lab in Austin, Texas, and an FDA COVID-19 certified test lab in Washington D.C. that was established by KorvaLabs, a company Curative acquired in May 2020. The company’s goal has been to scale up to one million tests every week. According to California Department of Public Health data, Curative has processed an average of 142,196 tests per week, 14% of its goal.”

Curative operated a pop-up testing kiosk in Berkeley in July. It has since become a permanent site at the Berkeley Adult School on San Pablo Avenue. Photo: Sarah Belle Lin

Curative’s testing kit instructs individuals to first cough deeply several times, and then swab around the inside of their mouth. Last April, a study by Curative, KorvaLabs, and UCLA showed that Curative’s test detected more cases of COVID-19 infection using the mouth swab method, but there were also three cases found using the nose swab method that hadn’t been found in the mouth swab samples. The researchers concluded that testing only the nose or the mouth might “miss some cases of Covid-19 infection,” but that nose swab samples did show greater amounts of the virus than seen in mouth swab samples.

This finding was supported by another study suggesting that nose swabs may be more accurate in detecting the virus. The Curative study, which the Alameda County Department of Public Health cites in its testing guidance, also had a relatively small sample size of 45 elderly symptomatic individuals, people with chronic diseases, first responders, and law enforcement officers, therefore it may not be generalizable to the broader public.

Curative was founded by 25-year-old Oxford-educated biotech entrepreneur Fred Turner to address the shortage of COVID-19 testing that has hampered the federal and states’ responses to the pandemic. A LinkedIn article states that Curative received six million dollars from investors, including Chris Anderson, the curator of TED, and former co-founder of Tinder, Justin Mateen.

Curative hoped to distinguish itself from other testing providers by offering a “painless” testing method. A Curative job posting states that within a year, Curative will conduct “5-10% of all COVID-19 testing through a network of over 10,000 testing sites” and that “we build our own software, develop our own tests, and run our own testing sites.” The website also claims it has a 100% test specificity. This means that Curative believes that 100% of their tests return “negatives” for individuals who truly aren’t infected.

By mid-October of last year, Curative announced it had tested five million people. On Dec. 18, Curative’s Chief Technology Officer, Lee Spraggon, tweeted that Curative had reached 10 million.

Agatha Bacelar, Curative’s general manager for California, tweeted in mid-November a table showing that Curative was processing more tests than any other lab company. According to the table, which Bacelar said was from the state Department of Public Health, 84 percent of people tested by Curative got their results within 24 hours, and that 100 percent had their results returned within 48 hours.

This isn’t the first time certain tests and test providers have been flagged for false-negative results. Last June, healthcare company Abbott’s ID Now, a rapid-test that produces results in 15 minutes, was reported to the FDA for an increasing number of false-negative reports compared to other tests, according to a document published by the Alameda County Department of Public Health. The FDA did not issue an advisory about the Abbott test.

The FDA reiterated in its press release that negative test results shouldn’t be the only measure of safe public health practices. Essentially, testing negative doesn’t give you a permission slip for people to violate social distancing guidelines and shelter-in-place orders. As the CDC and medical experts have been cautioning for months, safe and healthy practices mean wearing a face mask when out in public, placing at least six feet of physical distance between yourself and others, and avoiding large, especially indoor, gatherings as much as possible.

Some more options to get tested

Berkeley officials reiterated Friday that people should not rely on COVID-19 tests alone to keep them from catching the virus.

“Testing is an essential part of our response, helping identify cases for a virus that spreads easily,” the city said in a statement. “Along with recognition of COVID-19 symptoms, tests help identify when to isolate and quarantine. We also know that protective actions – such as staying home, wearing face coverings, avoiding crowds and keeping six feet from those not in your household – are essential because the virus may not be detected by any test for two weeks. People can get tested too early after exposure and become positive at a later point, unknowingly spreading it to others.

Update, Jan. 19, 5:10 p.m.: The original version of this story stated that Curative currently processes 25,000 tests per week or 2% of its goal. That was incorrect. The company has processed an average of 142,196 tests per week, 14% of its goal.