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Rapid COVID-19 Tests in Phoenix Aren't Necessarily Reliable

Copper Star Coffee has received media coverage for paying to bring in rapid COVID-19 tests. There are questions about the effectiveness of some of the tests.EXPAND
Copper Star Coffee has received media coverage for paying to bring in rapid COVID-19 tests. There are questions about the effectiveness of some of the tests.
Lauren Cusimano

Last month, Erika Skjei sat in the closed-down lobby of the coffee shop where she works. A medical professional employed by local vitamin company Hi-Health pricked her finger and drew the blood into a small, hand-held device. Within minutes she had her results: negative for COVID-19.

"It was pretty unbelievable, honestly," Skjei said. "It was a huge relief."

Thanks to such quick results, Skjei's employer of five years, the Melrose District staple Copper Star Coffee, was able to test the entire staff in a day and reopen after shutting down due to an employee's confirmed COVID-19 exposure. At the time, most standard COVID tests took two weeks to return results. That was too long, owner Bil Sandweg told TV news. So he shelled out $1,300 to get his staff tested by two private companies, allowing the business to reopen quickly and employees to start earning money again.

Average turnaround times have since dropped to a few days, but the value of getting test results in minutes holds great appeal for individuals and businesses. At a briefing last week, Arizona Department of Health Services Director Dr. Cara Christ said that weekly testing of employees was one of the measures that businesses closed due to the emergency orders — like gyms or water parks — could use to seek an exemption and reopen. Rapid testing could help in such cases.

When people talk about "rapid" COVID-19 tests, they're usually referring to one of four things: A handheld test that detects the presence of antibodies from a blood sample, like Skjei got; a standard nose-swab test processed with a small machine that can return results in less than 15 minutes; a swab or saliva sample processed by a dedicated private laboratory to avoid delays; or a self-administered mouth or nose swab processed with a kit at home in a few minutes, similar to a pregnancy test.

But while all these measures offer their own benefits and are likely to become more common, the effectiveness of most of the methods has drawn scrutiny.

Antibody Testing

The antibody test Skjei received could have missed an active COVID-19 infection. It can take weeks for antibodies — cells uniquely tailored to the infection they're meant to fight — to develop after infection.

Yet Hi-Health advertises that its testing service can "bring employees back to work safely," "identify employees with possible cases of Covid-19," and "help prevent community spread." Its Facebook page showcases some of the businesses that have used the service, including a chain of Mexican restaurants, another coffee shop, and a Phoenix law firm. The vitamin store offers discounts for weekly or bi-weekly tests and for large groups. Individual tests range from $55 to $85.

"You can't use the antibody test to see if you're actively infected," said Dr. Farshad Fani Marvasti, director of public health, prevention and health promotion at the University of Arizona’s College of Medicine-Phoenix.

The Centers for Disease Control and Prevention says the same thing: "Except in instances in which viral testing is delayed, antibody tests should not be used to diagnose a current COVID-19 infection," the centers' guidance reads.

When Phoenix New Times called Hi-Health's rapid testing number last week to get more information about its testing program, a man who answered said the company would have to consult with its public relations people before responding. In a follow-up call on August 12, the same person said that only the marketing manager could answer questions about the program, but she would be out of the office until an unknown time next week. A woman who answered the phone on Thursday morning told New Times she would pass along an inquiry to the director.

Although Hi-Health never responded, the antibody test the company uses appears similar to one manufactured by BioMedomics. While the tests do detect the IgM antibody, one of the first types of antibodies to respond to an infection, the median time for the COVID-19 variety to appear in one study was 12 days. For COVID-19's sibling, the SARS virus, it has appeared more quickly, but can still take up to a week to register.

"The COVID-19 IgM/IgG Rapid Test can be used to screen patients suspected of having been affected by the novel coronavirus," BioMedomics' website notes about its test. "However, results of [the] test should not be the only basis for diagnosis. Results should be used in combination with clinical observations and other testing methods such as nucleic acid PCR test."

Even if the test was only being used to screen for past infections, there's still no guarantee that people are immune after being infected once, and tests have been triggered by antibodies generated in response to cold-type viruses, Dr. Fani Marvasti said. He said the only "gold standard" for accuracy is the widely-used molecular test that's processed in a laboratory.

Copper Star Coffee's Sandweg said he wasn't worried about his staff, since it'd been a month since the potential exposure and they'd all also received results from standard nose-swab testing. If he were to hire private testing again, he said, he wouldn't do the antibody testing because it was more expensive than next-day lab testing.

Sandweg said he'd also want to look more into the information about testing. The two services he'd hired were ones that an employee and a customer had each heard about, and he got advice about testing from a doctor who is his best friend's father.

Point-of-Care Testing

Unfortunately, the results of a standard molecular test can sometimes take days to return from the lab. Currently, NextCare offers rapid testing as an alternative at eight of its 26 urgent-care clinics in Arizona using the Abbott ID NOW system. A rounded, white right triangle that looks a bit like an old-school iPhone docking station, it boasts the ability to return results in under 15 minutes from a nose swab.

The tests aren't available to everyone. A NextCare spokesperson didn't return a voicemail seeking more information about its rapid tests, but the Mesa-based company's website says that due to limited supplies, it's up to individual providers to decide if patients qualify for a rapid test or the standard test. The website lists potential criteria to qualify for a test as being symptomatic, an asymptomatic first responder or other critical worker, someone who has to return to work, or someone needing to undergo a medical procedure.

The ID NOW system isn't a magic bullet. Despite being hailed by President Donald Trump, who displayed one of the machines at a White House press conference in March, there have been repeated questions about the accuracy of the devices.

In May, the Food and Drug Administration released a warning that the devices could return false negatives — meaning that they would report someone was clear of the virus when they were, in fact, infected — and said it was looking into the issue further. Studies have found the machines detect anywhere from 91 percent to 50 percent of cases, although Abbott contests that last study. Most studies have found the device's accuracy to be in the mid-80 and 90 percent ranges.

The FDA said in its May release that it had worked with Abbott to send out a letter advising users that if a patient displayed symptoms that didn't seem to match the negative results of the test, the patient should get a standard test.

The Abbott test "can still be used and can correctly identify many positive cases in minutes," said Tim Stenzel, director of the FDA's Office of In Vitro Diagnostics and Radiological Health, said in the release. "Negative results may need to be confirmed with a high-sensitivity authorized molecular test.”

At-Home Testing


In the meantime, the FDA is opening the doors to at-home tests that could theoretically allow quick, inexpensive diagnoses. Known as an antigen test, it detects certain proteins that are part of the virus in as little as 15 minutes.

Dr. Fani Marvasti told New Times that while rapid antigen tests might not detect someone who has a lower concentration of the virus in their system, people with higher levels of the virus are more contagious and the rapid tests play a role in screening them out.

"Those are the people we want to catch," he said.

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Some have argued that at-home tests offer a more effective means of controlling the spread of the virus than the usual, more-accurate testing procedures because they can return results in time for people to act on them as soon as they become contagious.

Fani Marvasti said the tests are most effective if used repeatedly, as the amount of virus in a person's system fluctuates over time, but scientists still don't know whether the levels of the virus that make an infected person contagious are the same as those that would show up on a test.

The most important thing in the meantime is to continue social distancing, wearing masks, and to stay home if you feel sick, he said.

If you want to get tested in the Valley, you can find a location here.

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