San Antonio Express-News (Sunday)
Antivirus tests raise more questions than answers
Scores of brands released with little federal regulation
The idea behind antibody tests for the novel coronavirus is highly appealing.
Such tests, also known as serology tests, are designed to detect proteins produced by the immune system in response to an infection, indicating previous exposure to a pathogen.
The hope was that the tests, which use blood from a finger prick or blood draw, could identify people who had been infected by the coronavirus but never knew for sure. That presumed immunity could allow them to return to work and public life, without the risk of COVID-19 hanging over their heads.
But as antibody tests have proliferated in San Antonio and across the U.S., the reality of what they can and can’t promise consumers has proved far more confusing and complicated.
With little in the way of federal regulation, manufacturers have released more than 100 brands of antibody tests, with varying levels of accuracy. Few were vetted by the Food and Drug Administration before they went on the market.
Amid growing concerns about the reliability of some tests and false advertising of them, the agency ordered companies earlier this month to provide proof their tests worked and insti
tuted performance standards.
“I agree with anybody who says it’s a ‘Wild West,’ because there’s been a flood of different kits out there,” said Dr. Sam Bagchi, the chief clinical officer for Christus Health, which last month initiated antibody testing for its employees and selected patients at its hospitals.
Local health officials are sounding the alarm as dozens of antibody tests for the coronavirus have become widely available to the public through doctors’ offices, urgent care centers and driveup sites.
The tests are being marketed and sold to consumers who are desperate for answers about the highly contagious virus that has disrupted their lives and livelihoods.
Experts say existing antibody tests, still in their infancy, have limitations that prevent them from providing such insight. And they worry a positive test could lull people into a false sense of security, leading to less cautious behavior.
Dr. Junda Woo, medical director of the Metropolitan Health District, said the agency has been working to dispel the notion that antibody tests can diagnose a coronavirus infection, or that they can tell a person whether they are immune from future ones.
Not enough is yet known about how a person gains immunity to a virus that only has been circulating among humans for six months, she said, or how long such protection would last.
“It’s a public health threat for somebody to think that they’re protected and act as if they’re protected when they’re actually not,” she said.
Metro Health has created an explainer to help physicians grasp the complexities of antibody testing. While the health department is not responsible for regulating antibody tests, it is contacting providers who are conducting the tests outside a certified lab to warn them that they are violating federal standards.
The rushed roll-out of antibody tests has sparked a debate in the medical community about their usefulness for individuals. Some doctors recommend steering clear of them altogether, while others are using them as a screening tool or are counseling patients on the tests’ shortcomings and nuances.
Little regulation
The way that antibody tests entered the market was in sharp contrast to the cautious approach federal regulators took with diagnostic testing for the coronavirus.
When the coronavirus first emerged in the U.S., public health laboratories initially were unable to conduct swab-based diagnostic testing due to problems with kits distributed by the federal Centers for Disease Control and Prevention. Commercial and hospital labs also were unable to develop their own tests for some time, as the FDA was slow to grant authorization.
The resulting bottleneck, which was paired with initially narrow testing criteria, stymied early efforts to identify where the coronavirus was spreading.
With antibody tests, regulators allowed manufacturers to widely produce and distribute kits under a flexible policy issued in March.
As a result, tests went out to the public before developers had to prove their efficacy. And some began to falsely claim they’d secured FDA approval, when at best, only about a dozen tests had received emergency use authorization.
The FDA “allowed companies to provide antibody testing while they worked on providing the evidence that the antibody testing was doing what it said it was doing,” said Dr. Jason Bowling, an infectious disease specialist with UT Health San Antonio and University Health System. “The pendulum swings from one extreme to the other.”
Dr. Jeremy Gabrysch, CEO of Remedy, an Austin-based telemedicine company that has opened antibody testing sites in several Texas cities, said the FDA’s normal approval structure “cannot work in a pandemic situation, because it can’t get the lab tests we need to market fast enough.”
Two measures — specificity and sensitivity — are critical to understanding the strengths and weaknesses of any given test.
Specificity refers to the ability of a test to correctly identify all the people who have a certain disease — in this case, COVID-19. Sensitivity indicates how often a test accurately rules out those who don’t.
For the coronavirus, antibody tests have been all over the map. Some have been prone to detect antibodies for coronaviruses other than the one that causes COVID-19, such as those associated with the common cold.
The most accurate antibody tests still have limitations, Woo said, because there’s a higher likelihood of false positives if few people are infected. That could be a concern for people who get tested in San Antonio, where coronavirus infections account for less than 1 percent of the overall population.
“Even the best antibody tests will produce as many or more false results as true results if the level of infection in a community is low,” Woo said. “That’s not because it’s a bad test, that’s just a technical limitation of testing.”
Immunity a question
Some experts have noted that tests to diagnose an active coronavirus infection have drawbacks, too.
For that test, a swab is used to collect a sample from the nasal cavity. Depending on when a person is tested and where the virus is residing in the body, the test might not pick up an active infection, in some cases even for those who develop severe symptoms of COVID-19.
A person who’s almost or fully recovered might not test positive, either, if the virus mostly has cleared the system.
Even if antibodies are detected by a test, some experts argue that more needs to be learned about immunity against COVID-19, including which antibodies are protective and what level they must reach to confer that protection, before conclusions can be drawn from their results.
“We don’t know what the antibody to COVID-19 means, we don’t know how long the protection lasts,” Bowling said.
Based on information from other coronaviruses, such as the one that causes SARS, experts have estimated that immunity of two to three years after a COVID-19 infection is likely.
Some early success treating critically ill coronavirus patients with plasma from recovered donors also supports the idea that people infected with the virus have some level of immunity, Bagchi said.
“That does give us more evidence that immunity does exist and immunity can be shared through plasma donation,” he said.
But it’s still too early to say with certainty whether immunity against COVID-19 is like measles — robust and long lasting after infection — or something shorter, such as the flu.
Bowling said he wouldn’t recommend antibody testing for his patients at this time.
“I would not use it to diagnose their disease or try to interpret, from that standpoint, their individual health maintenance guiding their care,” he said.
Woo said she wouldn’t recommend people seek out such tests unless it was part of a study to identify coronavirus antibodies among the population at large.
Screening patients
Other health care providers in San Antonio see value in antibody testing and are forging ahead, albeit with differing approaches.
In early March, Christus Health, which operates hospitals in San Antonio and New Braunfels, began searching for an antibody test that could be used across its system.
They landed on an antibody test produced by Healgen Scientific, a Houston-based medical manufacturer, that produces results within 10 to 15 minutes. The system bought all of the company’s test kits — about 70,000.
The test, which has sensitivity of nearly 79 percent and specificity of more than 97 percent, was validated in Christus’ central lab against known coronavirus patients. Bagchi said the system never would rely on a test that had not been rigorously evaluated.
The FDA hasn’t yet given the test emergency use authorization.
The hospital system has chosen to deploy the antibody tests “as part of a comprehensive testing strategy and not a standalone test,” Bagchi said. They’re being used to screen Christus employees, including those who might have been exposed to the virus, as well as all consenting patients who are being hospitalized for elective procedures unrelated to COVID-19.
If a person tests positive for antibodies, they’re also then tested for active infection.
Bagchi said the testing can help ensure a safe hospital environment by flagging potentially infected patients and workers.
At Christus Santa Rosa Hospital at the Medical Center, the system also has piloted conducting both tests at the same time.
So far, more than 2,500 people throughout Christus’ international hospital system have been tested through blood draws. The tests are being offered at no charge.
There has been some debate about the testing among the system’s physicians, but Bagchi said most support it.
“We feel it’s important to use all the tools available to us to both expand our testing capacity and expand our understanding of who may have been exposed,” he said.
Alternate routes
Within the past few days, new providers of antibody tests have joined several dozen places already offering them in San Antonio.
Last week, Remedy, the Austin telemedicine company, began drive-up antibody testing at a parking lot off Interstate 10 on the Northwest Side. The company says the tests should be partly or fully covered by insurance but estimated an uninsured person would pay between $49 and $69.
While Remedy is conducting the blood draws, it has outsourced testing of its samples to Quest Diagnostics, a national commercial laboratory. Quest is using tests produced by Abbott Laboratories and Euroimmun, which have been granted emergency authorization use by the FDA.
Before patients are tested, doctors counsel them during a video call. Gabrysch said his company is trying to avoid problems with false positives by assessing patients for relevant symptoms and travel history. Such a targeted approach, as opposed to testing people indiscriminately, can yield more accurate results, he said.
“There are some things in medicine where we are able to tell you, this is exactly what this means,” he said. “There are other things where we have to say, this is what we think this means by the best evidence that we have.”
Gabrysch said he understands why health officials are worried about some of the problems with antibody testing. In Remedy’s case, he said, the company has prepared handouts explaining test results to its patients.
Other doctors have fully embraced making antibody testing available to the general public.
In late April, Dr. Luke Berry, a local emergency room physician, noticed a number of patients were unhappy with a dearth of testing for the coronavirus.
He obtained a mobile trailer and began researching companies that make rapid antibody test kits. On April 21, he began offering both diagnostic and antibody tests for the coronavirus at a price of $149 per person.
After moving around his testing site, Berry now has parked the trailer in front of Livingston Med Lab, a Stone Oak-area lab that processes the swabs he collects for the diagnostic tests. He said he has tested hundreds of people.
Berry, 31, who is affiliated with the Greater San Antonio Emergency Physicians group, said the cost of testing has been affected by skyrocketing prices for protective equipment, swabs and other items needed to run tests.
He sources his antibody test kits from RayBiotech, a Georgiabased biotechnology company. The tests, which use blood from a finger prick, are advertised as having sensitivity of around 90 percent and specificity of more than 98 percent.
At the bottom of his website, Berry has a disclaimer stating that the antibody test has not been reviewed by the FDA and that its results cannot diagnose a coronavirus infection. He noted the antibody tests are paired with the “gold standard” diagnostic ones.
“We disclose all of this, that there are limitations to the antibody test and immunity is not something we are saying this antibody shows,” he said. “The way that I was approaching it was, we can do these antibody kits and at least give the patient an idea if they were exposed.”
On Wednesday, Berry said he also soon will offer a finger-prick antibody test produced by Hardy Diagnostics, a California-based medical manufacturer that has received an emergency use authorization from the FDA. More of Berry’s tests would be conducted using those kits as they become available, he said.
Unlike tests for active infections, the results from antibody tests are not being reported to health departments, so they have no impact on official case counts.
Woo, with Metro Health, said she is concerned about some of the prices for such testing when diagnostic tests are available for free at numerous sites across the city.
“To ask people to pay 140 or however many dollars for a test that we don’t know will be useful is morally troubling, to me,” she said.