Top COVID-19 test scientist says there's no reason to stop using rapid tests

Rapid tests may perform differently with omicron, but they work, experts say.

December 30, 2021, 8:45 PM

With questions swirling about how well rapid COVID-19 tests work when it comes to detecting the omicron variant, leading scientists are now reassuring the public that they do work, and have a valuable role to play in the ongoing pandemic.

Among them is Dr. Bruce Tromberg, director of the National Institute of Biomedical Imaging and Bioengineering at the NIH, and the top scientist in charge of Rapid Acceleration of Diagnostics. RADx, a new government-funded NIH program, was tasked with rapidly increasing the nation's testing capacity and studying how tests perform when faced with new variants.

"The tests are an essential component of what we need, especially in the time of very rapidly expanding omicron," Tromberg said.

While PCR tests are very effective at detecting the presence of even small amounts of virus, rapid tests have become a quick and easy way to determine if a person is contagious. In a Tuesday announcement, the Food and Drug Administration said rapid tests do detect the omicron variant, but in a laboratory setting they did not perform as well as they have with earlier variants.

The FDA announcement, described by one expert as a kind of curveball, lacked specific numbers and sparked confusion and dismay among some experts and Americans who have been using rapid tests to reduce the risk of spreading COVID-19 to loved ones over the holidays.

Dr. Michael Mina, a vocal advocate for increased rapid testing use and the chief science officer for eMed, told ABC News, "There is no reason and no data to support that the tests are less able to detect omicron virus."

News from the FDA about rapid tests' ability to detect omicron comes on the heels of the Biden Administration's announcement that the U.S. will have 500 million at-home rapid tests available starting January.

But Tromberg said Americans should "absolutely not" be discouraged from using rapid tests based on this FDA announcement, which was based on preliminary laboratory studies on live virus samples combined from multiple patients and run on a relatively small number of rapid test brands.

PHOTO: People line up to take COVID-19 test at a free PCR & RAPID testing site in Chicago, Thursday, Dec. 30, 2021.
People line up to take COVID-19 test at a free PCR & RAPID testing site in Chicago, Thursday, Dec. 30, 2021. Illinois has 30,386 new COVID-19 cases diagnosed statewide, public health officials announced Thursday, smashing by more than 9,000 the previous state record for new cases in a day and nearly doubling the high from last fall's surge. (AP Photo/Nam Y. Huh)
Nam Y. Huh/AP

Those tests showed a potential dip in effectiveness, but, "It's not like they fell off the map," he said. The FDA also said more clinical studies are needed.

Preliminary studies conducted in a lab can off​er clues, but are not as reliable as real-world studies done on real people. Those real-world clinical studies are currently being conducted, and results should be available shortly, Tromberg said.

He expects clinical studies to show the tests are working at an acceptable level.

"We already know that the clinical performance is better than this laboratory benchtop performance, just in our early studies that we're getting."

"I have confidence that the tests that we have on our shelves can pick up omicron," Tromberg said. "There will be different levels of performance, we need to really work through all of those and understand them for every test."

One reason rapid tests might perform differently is because of the increased infectiousness of the new variant, said Mina.

"Is it that the test is less sensitive, or is the virus more infectious?" he said.

"Omicron is more infectious, and therefore, it is possible that people can start spreading the virus hours or a day before they are testing positive, but after that, the test will still work when people are most infectious just as they have been working throughout the entirety of the pandemic," Mina said.

Even if some rapid test performance is diminished, Tromberg said, "They still can be extremely powerful and effective at interrupting the chain of transmission of the virus."

The FDA has authorized 43 rapid antigen tests including at least a dozen at home versions.

Several testing companies have said their tests still work to detect omicron, with Abbott saying Tuesday that the company has tested the popular BinaxNOW rapid test using the omicron variant from live virus and found the test "performed at equivalent sensitivity" compared to prior variants.

But the FDA said tests could be updated if further testing shows updates are needed.

"Studies are underway to confirm the reason for the apparent decreased sensitivity," FDA spokespersons Stephanie Caccomo said. "Once that is known, adjustments to existing tests can be undertaken by each developer with support from the FDA, if appropriate."

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