Coronavirus California

ABC7 team tries out at-home COVID-19 antigen tests

If you're positive, you find out in minutes and can quarantine right away rather than waiting 48 hours or so for PCR test results.

ByKate Larsen KGO logo

Saturday, August 14, 2021

ABC7 team tries out at-home COVID-19 antigen tests

Abbott Labs came out with an at-home COVID test in 2020, but now with the Delta variant surging across the country, it's become a popular item.

SAN FRANCISCO (KGO) -- Abbott Labs came out with an at-home COVID test in 2020, but now with the Delta variant surging across the country, it's become a popular item.

Abbott's COVID-19 antigen test is $24 for a box with two tests, it takes just minutes to use, and there was plenty in stock at San Francisco Walgreens stores on Friday.

But do they work?

"After using tens of thousands of these tests at our Mission community site, we have a lot of confidence in the results," said Joseph Derisi, a UCSF professor of biochemistry and biophysics and co-president of the Chan Zuckerberg Biohub.

CZ Biohub ran a study at the 24th Street Mission BART station, comparing PCR tests (which are still the gold standard) to Abbott's Binax test and found: "for virus within the most infectious range, we found that the sensitivity was 99%."

Derisi says the Abbott test is so effective, it's now all they use at the Mission District testing site.

ABC7 News reporter Kate Larsen bought the Abbott Binax and Quidel Quickvue kits and tested them out in the newsroom with ABC colleague, Scott Spitz.

The Abbott test involves dropping a solution into a hole on a test card, swabbing yourself mid nostril (not the brain-busting swab with the original PCR test), and placing the swab in the test solution hole, and then waiting 15 minutes for results. The Quidel test has similar components to the Abbott test, with a different setup that involves a test strip and tube pre-filled with solution.

Both Larsen and Spitz tested negative for COVID.

"These direct antigen tests don't detect the genetic material of the virus, they detect the actual proteins that make up the virus," explained Derisi. "Basically, antibodies react on a little paper strip and turn color like a pregnancy test. So they're incredibly simple to use and incredibly simple to read."

"They can be very accurate. There is still some concern that with some of the tests, you want to be thoughtful about how to use it," said Sam Shen, a Stanford emergency room doctor, who says if users follow the instructions, the at-home tests are a powerful tool.

If you're positive, you find out in minutes and can quarantine right away, rather than waiting 48 hours or so for PCR test results.

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"It's giving people the ability to get information at home, closer to real-time, and it's decreasing the burden on the health care system to get tested," said Dr. Shen.

Derisi and Shen both explained that the two tests in the kits can be used by the same person for something called "serial testing," which is when the same person uses multiple tests to confirm results several days in a row. A fact sheet in the Abbott kit says "because antigen tests are less sensitive than other COVID-19 tests and false results may occur, repeated testing may identify more individuals with COVID-19 infection than a single test."

The kits are also helpful for COVID testing before, during, and after travel.

Derisi also says it's safe to use the at-home tests for safe social gatherings. "If you're having a dinner party or a birthday party for your kid. You can basically test everybody at the door and make sure and have that peace of mind that everybody coming for that day's birthday party is going to have no virus transmissible."

The FDA authorized both the Abbott and Quidel tests for emergency use.

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