What can Utahns really learn from a COVID-19 antibody test?

(Francisco Kjolseth | The Salt Lake Tribune) Lacy Deloach, who is 6-months pregnant, decides to get tested for COVID-19 antibodies after finding out that a friend had tested positive but never had symptoms, as registered nurse Jordan Eickbush pricks her finger for a blood sample at a drive up testing site at Galena Hills Park in Draper on Wednesday, May 20, 2020. She later found out she tested negative for antibodies.

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Draper • After a quick prick of her finger and a 15-minute wait, Lacy DeLoach hoped the blood test would finally tell her if she’d had the coronavirus.

The expecting mother had been sick at the end of January, about two months into her pregnancy, and tested negative for the flu. She’s been worried since, though, that she might have had COVID-19 at the time — even if it’s unlikely — and that it could have affected her baby.

“I just wanted to check,” she said. “I hope it’s negative. But I want some peace of mind.”

DeLoach was one of about 500 people who signed up and lined up Wednesday at Draper’s Galena Hills Park for antibody testing. The results are supposed to reveal a past infection by checking for antibodies the body has built up to fight against the virus.

Officials in Draper, along with those in Riverton, Bluffdale and Vineyard, said they set up the test sites to gather data about the infection rate in southern Salt Lake County.

But health experts have warned that antibody tests are not accurate enough to diagnose individuals — and scientists do not yet know whether a patient with antibodies is immune or protected from COVID-19.

“In addition, there is a chance of false-positive results from COVID-19 antibody testing, especially in settings where there is a low prevalence of COVID-19,” said Tom Hudachko, spokesman for the Utah Department of Health.

'Waiting to see what it means’

Still, Draper Mayor Troy Walker said, “I’m hopeful we’ll find some people who have it but don’t know they have it because they were asymptomatic. We need to know so we can get a good look at our infection rate.”

The four cities quickly filled appointments for the 2,500 tests they secured from RapidScreen Solutions, a company first registered with the state last month by a Layton oral surgeon, according to state documents. The company charges each patient $70, which is then given to the cities to reimburse them, Draper officials said. The patient gets results at the test site, and the cities will receive aggregate data.

“I don’t know what we’ll do with it, to be honest with you,” Walker said. “I think everyone is still waiting to see what it means. If there’s a bunch of people with antibodies, some health entity will have to say, ‘These antibodies mean this for you.’ ”

Olympus Health & Performance, based in Holladay, is also offering antibody testing, including a mobile service that goes to businesses or homes, it said in a statement. And other organizations are conducting antibody testing in Utah for clinical and research purposes.

The University of Utah is testing 10,000 people randomly selected in four counties to gauge infection rates. And Intermountain Healthcare is focusing on patients whose symptoms have persisted despite a previous negative COVID-19 test, as well as health care providers.

“Widespread, community-based antibody testing should only be done in collaboration with trained epidemiologists and researchers,” Intermountain wrote on its website.

The value of nonrandomized, community antibody testing depends on the number of people being tested, Hudachko said.

“If they were able to test a large portion of the residents in a particular area, then yes, nonrandomized testing could be useful in determining the magnitude of spread,” Hudachko wrote. “If it’s a smaller sample size, then the data may not be as useful from a public health/research perspective, but the results could still be important and useful on an individual basis.”

Experts urge caution

For the most part, though, state experts warn, antibody tests are “best used for scientific research.”

They are particularly prone to false-positive results among asymptomatic people, the Food and Drug Administration says. And of the 13 antibody tests approved by the FDA for emergency use, the one that showed the highest chance of false positives is the one being used at the four cities’ test sites.

It also is a finger-prick test, which state health officials have said may be “unreliable.” Tests that are based on a blood draw are considered more accurate.

“We didn’t get involved in which test to select,” Walker said. “We were working with RapidScreen [Solutions].”

Dr. Paul Benson, the company’s registered agent, said of the small number of companies with emergency use authorization from the FDA, “U.S.-based Chembio has the only rapid screen solution,” using a finger-prick method to collect blood rather a blood draw.

Its “95% accuracy is very good,” he aded, noting that, “accuracy depends on how long the person was exposed to the virus: for those who were exposed a long time ago, New York-based Chembio is showing 100% accuracy. If they were exposed three days ago, the human body may not show that. For mass antibody testing, Chembio’s tests are the best option.”

Regardless of the test, the FDA wrote, a single antibody test on an asymptomatic person “is not likely to be sufficiently accurate to make an informed decision whether or not an individual has had a prior infection or truly has antibodies to the virus.”

Draper and the other cities with the antibody testing sites are supplementing any positive result with a saliva test for an active infection, city officials said.

But on its website, RapidScreen Solutions promotes a longer-term benefit of antibody screening, describing it as playing “a critical role in confirming workers are ready to return to their normal duties without further risk to themselves or others.”

State health officials have been more hesitant.

“Since we don’t know at this time if antibodies provide immunity against COVID-19, employers should not require their employees to have a positive antibody test in order to come back to work or reopen their business,” states the Utah coronavirus website.

Tests are in demand

But a lot of Utahns urgently want any tool that can shed light on whether they’ve had the coronavirus. In Draper, cars stretched down the long gravel parkway in four different lanes. Tens of nurses and lab technicians stood at their windows ready to go. A small group was playing soccer in the field nearby. Everyone was wearing masks.

Jordan Eickbrush, a registered nurse, waited for DeLoach to roll down her window and then stuck DeLoach’s finger, drawing some blood. Eickbush put that in a vial with some solution. It sits there for five minutes and then is transferred into another solution for 10 minutes. After that, it should produce results.

Those show up on a tiny white card with red lines indicating whether there are antibodies present. Positive results usually indicate past infection, but depending on the ratios of two different types of antibodies, they could also show current sickness. That’s why there are the additional saliva tests.

“I know it’s not perfect,” Walker acknowledged. “There is no perfect test.”

But, he said, the four cities are considering kicking in for 1,000 more tests after the first supply sold out within two days.

“There are quite a few people who think they were exposed,” Walker said.

DeLoach said she was relieved to learn she probably was not one of them. Her result was negative.