'Trying to catch every case': Are cheap home COVID-19 tests the delta antidote?
In the isolated villages dotting the tundra of southwestern Alaska, a plane ride away from the nearest public health lab in Anchorage, it took an average of eight days to complete a coronavirus test last October.
Public health workers stepped in, and beginning in mid-November they blanketed the Yukon-Kuskokwim Delta region with 15-minute coronavirus tests. The tests were completed, outbreaks slowed and cases dropped 65%.
But now, with a nationwide shortage of the Abbott BinaxNow testing kits and a delta variant-driven testing surge, health workers there last week learned that their next shipment would have far fewer test kits. In a region vulnerable to COVID-19 because of crowded households, a lack of running water and indoor plumbing and large numbers of people with underlying health conditions, officials are worried.
"I’m hoping we won’t get to the point where we really start limiting the number of people we test," said Dr. Ellen Hodges, chief of staff at the Yukon Kuskokwim Health Corporation. "Everyone in America is worried about that, not only us up here."
Rapid antigen tests made by Abbott Laboratories, Quidel and Ellume are cheap, don't need prescriptions and have been sold for months by major retailers. More recently, three more rapid antigen test makers have received Food and Drug Administration authorization to sell home tests directly to consumers.
The two largest manufacturers, Abbott and Quidel, slowed production this spring as coronavirus cases dropped significantly. Ellume secured a $231.8 million Department of Defense deal to expand U.S. production, but the Australian company has not yet opened a planned U.S. factory in Maryland.
And although the Biden administration sought to kick-start coronavirus screening in schools with $10 billion in American Rescue Plan funding, few states and schools have implemented widespread screening. U.S. Rep. Kim Schrier, D-Wash, has demanded answers about how the money is being used for school testing.
Struggling to find coronavirus test?You're not alone, thanks to the delta variant
Still, with labs in hot-spot communities once again scrambling to meet a spike in testing demand, advocates say rapid tests that don't require a lab can serve a crucial role as the delta variant sends case counts and hospitalizations higher.
"It's absolutely a second wind in a lot of ways," said Dr. Michael Mina, a Harvard epidemiologist, who has long pushed widespread use of rapid testing.
The Centers for Disease Control and Prevention said even vaccinated people should get tested if they're exposed to someone with COVID-19, a reversal from its earlier guidance. Abbott and Quidel are once again ramping up factories after slowing production earlier this year when demand dipped and cases dropped as more Americans got vaccinated.
These coronavirus tests have trickled out since August 2020, when the federal government purchased 150 million Abbott kits for use in nursing homes, schools and other settings with medical oversight.
The rapid antigen tests detect proteins on the surface of the coronavirus but are less likely to find a case than lab-based PCR tests that detect a virus’s genetic material. Unlike the lab tests that typically take one or two days to complete, depending on how quickly samples are shipped and how busy the lab is, the rapid antigen tests typically deliver results in 15 minutes or less.
'Almost everyone in the village had gotten infected'
Hodges oversees staff of a health care system in Bethel, Alaska, a city that serves 46 villages scattered in a region the size of Oregon.
She was initially hesitant to use antigen test kits because she was concerned about accuracy. But last fall, Bethel had limited laboratory testing capability. Health teams would need to collect samples from patients in remote and isolated villages and fly those samples 400 miles to a lab in Anchorage. In some communities, it took 10 to 15 days to get results, too slow to counter a fast-moving virus.
An outbreak last October and early November went undetected in Chevak, a village of about 1,000 people near the mouth of the Yukon River in western Alaska.
"We didn’t know there was a problem until almost everyone in the village had gotten infected," Hodges said. The outbreak prompted her to deploy the Abbott tests.
Beginning Nov. 9, she said, health workers began to use the tests in "every village we could." The results were immediate. The Abbott tests detected 37% of all new cases in the region from Nov. 9 through March 1, and overall cases dropped threefold, according to a recent CDC report.
Public health workers send teams to remote and isolated villages to test as many people as possible, using both Abbott and PCR tests.
Hodges said false negative results "are a really big problem," so a person who has symptoms or is exposed to COVID-19 is tested again if the first test does not find the virus. The more sensitive PCR tests are used on people exposed to the virus but do not show symptoms.
Public health workers rely on steady shipments of the Abbott tests to complete 1,000 to 1,200 rapid tests each week. When ordering more tests last week, they were told to expect fewer kits than typical shipments, she said.
Hodges said her team now has the lab equipment to run more PCR tests in Bethel, eliminating the need to fly samples to test in Anchorage. But she does not know if she will get enough Abbott tests over the coming weeks to maintain their current pace.
"I am concerned about it because it really is a cornerstone of early identification of cases in villages," she said.
'Vaccines aren’t the silver bullet out of this'
Mina believes the testing shortage is a symptom of an uneven federal response to the virus. Major test makers pulled back from production this spring because the CDC did not recommend that vaccinated people get tested even with symptoms.
Mina has long pushed for the federal government to purchase enough rapid antigen tests so most Americans can test two to three times each week. He argues even though the tests are less sensitive than lab tests, they detect cases when people are infectious and most likely to infect others.
With the delta variant sending case counts higher, he said there's "renewed interest" in widespread testing.
"People are realizing vaccines aren’t the silver bullet out of this," Mina said. "They are an absolutely crucial and important piece. But they were never going to be the thing that stopped the pandemic because we’ll have breakthroughs, variants and waning immunity."
Though major retailers such as Amazon and Walmart have reported spot shortages of rapid tests, some vendors say tests are still available.
The telehealth provider eMed markets the BinaxNow test for $25 to people with COVID-19 symptoms. The test is available through a mobile phone app, which instructs users to fill out a screening questionnaire reviewed by an eMed representative. Test kits are shipped to eligible customers who access eMed's portal for testing guidance.
CEO Patrice Harris said her company has access to millions of tests and has noticed a surge in orders from people who need a test for an international flight and businesses testing employees.
She said an eMed representative guides customers through every step in the testing process: opening the box, swabbing their nose to get a good sample and inserting the swab in the testing card. These guided steps can increase the likelihood the person completes the test correctly and gets accurate results.
"We want to make sure it's a valid test," Harris said.
Over-the-counter tests generate complaints
Consumers have described mixed results with home tests that can deliver results in 15 minutes and do not require a lab.
Several customers who purchased the Ellume COVID tests have complained on consumer review boards about “false positive” results when compared with laboratory-based PCR tests.
In December, Australia-based Ellume became the first company to gain FDA authorization to sell consumers kits that don't require a prescription and deliver results in minutes. The Ellume kits cost $35 to $39 at major retailers such as Walmart, CVS, Target and Amazon.
Ellume’s top executive acknowledged some customers are getting false positive results. CEO Sean Parsons said Ellume’s test is calibrated to detect more cases than other rapid antigen tests.
“When we develop these products, we had erred on the side of catching every positive,” Parsons said. “We are trying to catch every case. In doing that, we do have a small rate of positives that aren’t confirmed by PCR.”
Several consumers have written complaints about false positive results on CVS and Amazon’s customer feedback portals. Some described the anxiety of believing they contracted the virus and might have exposed others before taking follow-up tests to discount the results.
Parsons said he has talked with consumers who’ve lodged complaints about false positive results, and he sympathizes. These are customers who are trying to check their status before visiting family or loved ones so they can avoid possibly spreading the virus, and they are frustrated when positive tests aren't confirmed by non-Ellume tests.
Parsons said the company has discussed with federal regulators possible updates "to the decision-making process of the test" and "we hope that with their blessing, we’ll be able to roll that out in the future."
But he said the kits are highly accurate and are performing to levels demonstrated in studies submitted to the FDA.
When used on people with symptoms, Ellume correctly identified 96% of positive samples and 100% of samples without the virus compared with a lab-based PCR test, according to a clinical study. Ellume's accuracy figures dropped when used by people without symptoms; 91% of positive samples and 96% of negative samples were correctly identified.
Like all coronavirus tests, accuracy also depends on how widespread the virus is in a community. False positives are more likely to occur when a community has low levels of the virus. In a community where just 1% of residents have COVID-19, a person who tests positive with the Ellume home test is more likely than not to have a false positive, according to the FDA.
The FDA recommends anyone who tests positive but does not have symptoms take a lab-based test to confirm results.
Other home tests made by Abbott and Quidel contain kits with two tests to be administered over three days, a serial screening strategy designed to make the tests more accurate. Three other companies – OraSure, Access Bio and Becton, Dickinson – received FDA authorization to sell home kits for two tests over two or three days.
By greenlighting the rapid antigen tests and other home testing technologies, the agency significantly expanded access to testing for Americans.
The FDA monitors the accuracy of all over-the-counter tests and has no concerns about the performance of any authorized test, spokesman James McKinney said.
"It is important to note that (home) tests for COVID-19 are typically less sensitive and specific than lab-based tests, and all tests can produce false positive results," McKinney said.
Parsons says consumers who purchase Ellume test or kits made by other manufacturers are learning how to better use the tests.
"America and consumers are learning about how these tests can be best used, and their strengths and their blemishes," Parsons said. "All of the products out there have these blemishes. We certainly have been very upfront about doing the very best we can for our users, and we’re looking to improve the places where we think we can make the improvements."
Lab scientists stress accuracy
Lab experts warn that direct-to-consumer tests can confuse consumers with inaccurate results.
Dr. Patrick Godbey, president of the College of American Pathologists, said some antigen tests might miss cases. In such cases, a person who tests negative but really has the virus might spread it to others and not seek treatment.
But he said false positive results also can create unnecessary angst or divert resources through follow-up tests or medical appointments. That can create extra work for hospitals or health systems already struggling to care for the rising numbers of COVID-19 patients.
"It not only distresses the patients but causes them to do things that are not necessary," Godbey said.
Geoffrey Baird, acting chair of laboratory medicine and pathology at the University of Washington, said recent studies of mass screening of athletes in the Pac 12 and Big Ten conferences show the tests are too inaccurate to be reliable.
"Most of the positives were going to be wrong, and most of people’s COVID were going to be missed," Baird said. "That is how it was always going to be. That’s what those numbers of sensitivity and specificity mean."
Ken Alltucker is on Twitter as @kalltucker or can be emailed at firstname.lastname@example.org.