Where can I get a COVID-19 antibody test and is it reliable? Here's everything you need to know.

Coronavirus antibody testing in the U.S. is starting to ramp up as government officials discuss when they can reopen communities and health experts survey hotspots.

From coast to coast, epidemiologists are using some of the many antibody tests that have entered the market recently to determine how much COVID-19 has spread. 

The importance of these tests are not lost on Americans, who are itching to go back to work, see loved ones and find out if they have been infected with the virus. Many have questions about where to find antibody tests, how they work and if they can even be trusted. 

There aren't easy answers. With little public data about the tests' accuracy, experts question whether they will give people false reassurances by indicating they have immunity to the disease.

What is an antibody test?
Testing to see if people have antibodies in their blood isn’t the same as testing to see if they are infected with the coronavirus that causes COVID-19. 

An antibody test can determine if someone has been infected and recovered, whereas a molecular test – a "PCR" test that usually uses a nose or throat swab – shows whether that person was infected with the virus at the time the test was taken. 

Antibodies are the body’s way of remembering how it responded to an infection so they can attack again if exposed to the same pathogen. If a person has antibodies in her blood, that means she has immune cells available to fight the virus, which lowers the risk of getting sick.  

How does a COVID-19 antibody test kit work?
The blood tests for COVID-19 look for antibodies specific to this coronavirus. Health care workers take a sample of a patient's blood and isolate the parts containing the antibodies into a serum. If someone has coronavirus antibodies, they would be found in the blood, along with other antibodies.

Some tests use a simple finger prick to draw a blood sample, which is collected with a thin straw and deposited in a small cartridge along with a special solution of liquids that will cause a reaction. Ten minutes later, the test promises to tell you whether you've had COVID-19.

Why antibody testing is important
In theory, antibody tests can reveal who is immune to a disease. They can also determine how widely it has spread and how deadly it is.

Broad testing of even a portion of the population in the coming months could give researchers a sense of how many Americans have been infected. They could use that to predict who might be immune if COVID-19 cases spike again this fall.

A team at Innovative Express Care processes patients before administering antibody testing in Chicago, Ill., on April 24, 2020.

Antibodies for similar coronaviruses can be present in the body for a couple of years, said Dr. Liise-anne Pirofski, professor of biomedical research at the Albert Einstein College of Medicine. However, scientists don't know how long antibodies for the new coronavirus remain in the body, and how much is required to be immune. 

Antibody testing is also important because people with the antibodies may qualify to donate blood that can be used to manufacture convalescent plasma, an experimental treatment for people who are seriously ill from COVID-19.

But there are many questions about the tests now available.

When will antibody testing be available to the public?

The Food and Drug Administration has issued emergency use authorization to just four serological tests developed by Cellex, Chembio Diagnostic Systems, Ortho Clinical Diagnostics and Mount Sinai Laboratory. The FDA said it expects to authorize more in the coming weeks.

Emergency use authorization allows unapproved medical products to be used during a public health crisis, without the benefit of the validated testing that would normally take place.

More than 100 tests are coming on the market, but the vast majority has not been authorized by the FDA. In March, the FDA allowed companies to sell antibody tests if they conduct internal evaluations of the tests and notify the FDA. The FDA did not review those tests, as it typically would, in an effort to put them in use as quickly as possible.

"There’s even more concern there. They’ve had even less regulatory control," said Dr. Greg Poland, director of the Mayo Clinic's Vaccine Research Group. "How are manufacturers testing these? Are they rushing these out prematurely? That economic motive is what requires regulatory oversight."

Under the FDA's updated policy, dozens of new antibody tests are being marketed without emergency use authorization. So while tests are becoming available to the public, they haven't received much scrutiny.

Dr. Stephen Hahn, who heads the Food and Drug Administration, said earlier this week that his agency and others are examining some of the antibody tests offered by manufacturers.

Is there COVID-19 antibody testing near me?

Depending on where you live, you may not have access to antibody testing. Most people can't drive up to their local pharmacy, lab or hospital and ask for an antibody test.

However, some private labs are offering antibody tests to the public, with or without a doctor’s referral, for a fee. These include labs such as ARCpoint Labs in Greenville, North Carolina ($75), National Jewish Health in Denver, Colorado ($94), and Innovative Express Care in Chicago ($250).

Wegmans antibody testing: New York does statewide testing

Some states have set up antibody testing sites for a limited number of people. The New York State Department of Health recently conducted a statewide survey that tested 3,000 people in 20 different grocery stores, finding that 13.9% tested positive for the antibodies. That would mean 2.7 million residents could have had the virus already. 

Skokie resident Ken Rzepecki waits in line to get an antibody test at Innovative Express Care in Chicago, Ill., on April 24, 2020.

The study suggests a death rate of about 0.5% of those infected because about 15,500 New Yorkers have died of confirmed COVID-19 cases, and there are about 19.5 million people in the state.

Gov. Andrew Cuomo said the results are an important indicator of the spread of the virus, though the death rate is probably higher than the results showed.

"It’s still preliminary, and when we say there are 15,000 deaths, those numbers are going to go up," Cuomo said. "These are only hospitalization or nursing home deaths. It does not include so-called at home deaths."

Epidemiological experts don't know enough to make sweeping generalizations on the study, Pirofski said during a teleconference hosted by the Infectious Diseases Society of America.

"We need to slow our roll; these tests have not been available for that long," she said. "This is our first dive into understanding what’s coming, and the deeper dive is coming."

Red Cross antibody testing

The Red Cross announced Thursday it is seeking people who have fully recovered from COVID-19 to sign up to donate plasma (which contains antibodies) to treat current COVID-19 patients.

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Donors must meet certain requirements to donate, including having a prior, verified diagnosis of COVID-19. Pirofski said the donor must have documentation, such as a positive PCR test or an official isolation order, and can donate up to 28 days after the resolution of their symptoms. 

This is not a diagnostic test to determine if you had the virus in the past. 

How reliable are antibody tests?

Researchers have raised many questions about the accuracy of antibody, or serology, tests.

"Nobody’s done what I would call a thorough head-to-head comparison with a validated gold standard," Poland said. "I’m actually surprised that some of these kits can be used clinically."

Poland said he's concerned about the tests giving false positives.

"One of the things I’m afraid of is that people are going to go to drive-thru testing who have not had (the) disease and are going to be told that they’re protected" because the test shows they have antibodies. "And they’re going to act and react according to that misinformation. That’s a problem."

For instance, a positive result could mean a test detected antibodies developed from exposure to other coronaviruses, not COVID-19. “We want to make sure you’re not having any cross-reactivity” to other viruses, said Kelly Wroblewski, the director for infectious diseases at the Association of Public Health Laboratories.

A key question is the "specificity," or the false-positive rate. For instance, a specificity rate of 98% suggests a test would report just two false positives out of 100.

However, biochemists and infectious disease experts say the false-positive rate should be considered in relation to the prevalence of the virus in the community. If few people have actually contracted the virus, there will be more false positives. Those people may think they're immune when they're not.

Another issue is that testing positive for the presence of antibodies doesn't mean you have enough antibodies to be immune. Researchers don't know how many antibodies would confer immunity, assuming it does.

A team at Innovative Express Care processes patients before administering antibody testing in Chicago, Ill., on April 24, 2020.

"When you say positive, what does that mean? The lower limit of detection? Or a high enough level that you’re protected? What they don’t say, and they should, is does this result mean I’m protected?" Poland said. "It’s a difficult discussion because people leap to the idea, 'Oh, I have antibodies, so I’m safe.' But by some of these (tests), the odds are a flip of a coin. That’s inherently dangerous."

Many larger institutions, including the Mayo Clinic, are now creating their own antibody tests because they've found others to be unreliable, Poland said.

"The science has not kept up with the test," said Dr. Mary Hayden, professor of Internal Medicine and Pathology at Rush University Medical Center. "The tests are out there but we need to do research to understand what the tests mean."

The World Health Organization issued a warning Friday, saying that antibody tests "need further validation to determine their accuracy and reliability."

"There is currently no evidence that people who have recovered from COVID-19 and have antibodies are protected from a second infection," the statement said.

Questions about FDA's oversight of antibody tests

Dozens of serology tests have not received FDA emergency use authorization, and some are falsely marketing themselves as having received authorization, according to the FDA.

"Be aware that not all marketed serological tests have been evaluated by the FDA," the agency said in a letter to health care providers. "Some firms are falsely claiming that their serological tests are FDA approved or authorized, or falsely claiming that these tests can diagnose COVID-19."

The FDA said it's working with the National Institutes of Health and the Centers for Disease Control and Prevention on a "validation project" to help identify the most promising serological tests.

On Friday, a House subcommittee issued preliminary findings of a review of antibody tests and government oversight. It said the White House's plans to reopen the U.S. economy “are flawed by their dependence on coronavirus antibody tests, which face unanswered scientific questions of utility and accuracy.”

The findings, sent to the Democratic staff of the Subcommittee on Economic and Consumer Policy, said the FDA did not review any coronavirus rapid antibody test kits before they went on the market. The oversight gap “has allowed manufacturers to make fraudulent claims about their efficacy,” the memorandum said.

Several companies appeared to have violated FDA regulations by offering at-home antibody tests and tests outside the purview of certified high-complexity labs.

Hahn did not offer a detailed response when asked about the memorandum during a Friday evening news conference of the White House Coronavirus Task Force.

Is antibody testing the key to reopening the economy?

If we're able to test people for antibodies, the theory goes, we can figure out who is immune and can go back to work. Or, for health care professionals and first responders, we can figure out who can stay at work.

But the questions about antibody testing mean we're not close to that being reality.

"The whole presupposition around the testing is, on the one hand, they have central importance in reopening, and on the other hand, there are complete unknowns," Poland said. Among them: "Is the test accurate? What does it mean? How long might someone be protected that has a positive test?

"This is all resting on a very shaky foundation," he said.

If antibody tests reveal a community has developed "herd immunity" — that's when a large portion of the population becomes immune to a disease or virus, inhibiting its spread — then states may be able to lift lockdowns and more Americans could return to work, some argue.

Tolbert G. Nyenswah, Senior Research Associate at Johns Hopkins Bloomberg School of Public Health, believes achieving "herd immunity" in the U.S. isn't realistic given the size of the population and the relatively small number of people who have recovered from the coronavirus. There are about 330 million people in the U.S., and about 885,000 people have contracted the coronavirus as of Friday afternoon, according to Johns Hopkins University.

Some criticize relying on "herd immunity" because they believe it's a passive solution to the pandemic that could cost more lives and overload the health care system. 

John C. Welch, director of Partnerships & Operations for the Massachusetts COVID Response at Partners in Health, leads a statewide contact tracing effort and has firsthand experience combatting infectious disease such as the Ebola epidemic in West Africa. 

"To talk about herd immunity is sensationally offensive," he said. "Herd immunity assumes you're okay with people dying."

'I want to know if I had it'

At Chicago's Innovative Express Care on the North Side, dozens of people had lined up in cars and on foot by 9 a.m. to get an antibody test. It was 40 degrees, and many wore hats and gloves.

"I want to know if I had it because I was sick from November to mid-January, and so was my entire family," said Lincoln Park resident Amber David. "If it's like most viruses, if you get it again, it's not as bad. That's my thought process. I won't be as concerned. ... If I know that I had it, I already know what I dealt with, so I know my kids didn't end up on a ventilator."

A health care worker at Innovative Express Care processes patients before administering antibody testing in Chicago, Ill., on April 24, 2020.

Fellow Lincoln Park resident Natalie Patterson said she had experienced chest pains and a cough at the beginning of March.

"I'm hoping that I already had it and recovered. Put my mind at ease. I would have known how my body reacted to it – that I already had it and it wasn't terrible," she said.

Patterson said she hoped her three kids already contracted the disease, too.

"My youngest son has asthma, so, at this point, I kind of hope that he was exposed but had no reaction," she said.

Skokie resident Ken Rzepecki said he hoped to get proof of immunity so he could visit his grandchildren. "I figure, it's a walk-up test. I'll come and get tested and see if that helps me go see the kids," he said.

Chicago resident Tony Unruh said he and his girlfriend were sick in February while visiting Colorado. They sought the test so they could donate plasma. 

A team at Innovative Express Care processes patients before administering antibody testing in Chicago, Ill., on April 24, 2020.

Many of the people lined up to get an antibody test were aware of the uncertainties. For most, a potentially flawed answer was better than nothing at all.

"I figure that it's early, and if this test ends up being the one that everybody wants, it's better that I got it sooner rather than later," Patterson said.

The clinic began offering tests Wednesday. The online booking system immediately filled up.

"Within a day, we were booked till May 31st," said Dr. Rahul Khare, founder and CEO of Innovative Care. "The website crashed."

The clinic completed 150 tests Wednesday, followed by another 250 Thursday, Khare said. 

Innovative Care initially said it was using a test by PerkinElmer, and that it had received FDA emergency use authorization.

When USA TODAY pointed out the FDA hadn't authorized that test, Innovative Care said it would update its website.

The lab later said it was actually using a test by Abbott Labs. The FDA has not given emergency use authorization to an antibody test made by Abbott.

Later Friday, the company removed any reference to what test it was using.

Contributing: Kevin McCoy

Reference: Yahoo News