In-Depth: The simple change that made rapid COVID tests reliable

Over-the-counter rapid tests get FDA go-ahead
Rapid COVID self-test
Posted at 6:12 PM, Apr 01, 2021
and last updated 2021-04-18 21:43:02-04

SAN DIEGO (KGTV) -- COVID-19 self-tests that offer on-the-spot results in minutes will start hitting pharmacy shelves this month, with no prescription required.

The Food and Drug Administration granted emergency authorization Wednesday to at-home antigen tests from Abbott and Quidel, which is based in San Diego.

Quidel said its tests would become available in certain pharmacies early this month. Abbott said its tests would hit the market in the next few weeks.

The authorization from the FDA represents a significant endorsement that rapid diagnostics are accurate and effective in even the most challenging testing scenario: evaluating people who are not showing symptoms.

“The public can be assured these tests have met our scientific standards for emergency use authorization. As we’ve said all along, if it’s a good test, we’ll authorize it,” said Jeff Shuren, director of the FDA’s Center for Devices and Radiological Health, in a statement.

Throughout the pandemic, many doctors believed the only reliable way to detect infections in asymptomatic individuals was to use a PCR test, a diagnostic that requires processing in a lab and returns results in one or more days.

However, emerging evidence suggests rapid antigen tests are also effective on asymptomatic people as long as they test serially, meaning the individual takes a follow-up antigen test 24 to 36 hours after the first.

The tests from Quidel and Abbott will be sold in two-packs. Prices have not been set but the two-pack from Quidel is expected to cost less than $30, according to CEO Douglas Bryant.

“Because I know that the virus grows quite rapidly, if I missed it the first day, 24 to 36 hours later I'm going to pick it up,” said Bryant in an interview. “So, in effect, I have a great ability to detect the virus early before that individual can go out into the community and spread the disease.”

A study at the University of Illinois on mild and asymptomatic cases found that when Quidel’s rapid test was administered at least twice a week, its accuracy jumped to 95 percent. The study, like many during the pandemic, was published to a pre-print server meaning it has not yet undergone peer review.

“We believe this is the beginning of an era of frequent testing in order to demonstrate that we're ready to go back and reopen the economy,” Bryant said.

These rapid tests aren’t just more convenient, one study published in Science showed they can have a big impact on slowing the spread.

In November, Slovakia rolled out rapid tests on a mass scale, testing more than 80 percent of its population in certain counties. The researchers found infections dropped 58 percent in one week. After the second week, infections were down more than 80 percent.

This was an observational study, not a randomized controlled trial, so the authors noted that other social distancing measures may have contributed to the decline. But they noted that lockdowns without this widespread rapid testing were much less successful. The UK went into a month-long lockdown in November and only reduced cases by 30 percent.

Quidel is now trying to see if it can replicate those results in the United States.

The company just announced it is partnering with the National Institutes of Health to test the impact of repeated, rapid testing in parts of North Carolina and Tennessee.