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News about coronavirus in Florida and around the world is constantly emerging. It's hard to stay on top of it all but Health News Florida and WUSF can help. Our responsibility at WUSF News is to keep you informed, and to help discern what’s important for your family as you make what could be life-saving decisions.

Florida Residents Are Getting More and More Antibody Tests. Do They Know What The Tests Mean?

A Miami-Dade County firefighter has blood drawn for an antibody test at Hard Rock Stadium in May.
A Miami-Dade County firefighter has blood drawn for an antibody test at Hard Rock Stadium in May.

The day of her 38th birthday in April, Jane Castro decided it was time to finally find out if she’d contracted COVID-19 during a January trip to Arizona State University.

During the trip, the university announced that a man on campus in his 20s had become just the fifth case of the new virus in the United States. Castro got sick once she was back in Miami Beach. But at the time, there was bigger news: Kobe Bryant had just died in a helicopter crash with his daughter. In Florida, the virus barely made news.

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That changed quickly in the weeks that followed. By mid March, Florida was beginning to shut down. Ultra was cancelled and Castro’s worry, along with her confusion, mounted. 

“I have friends who are telling me, oh, no, positive is a good thing. You’re immune,” she said.

So she visited a walk-in clinic. Three days later, the results came back negative.

     View this post on Instagram          On Monday May 4th - I wanted to go get the antibodies test at Medrite Urgent Care - Miami Beach - it's a walk in - it's free for everyone doesn't matter if you are not a Miami Beach resident and you don't need insurance - doesn't matter if you don't have symptoms - it's a blood test and you get the results in 3 days - I got my results today Thursday May 7 and I am Negative - I did the Swab test on April 4th because I was in Arizona for work late January and I got sick early February though it lasted 3 days - then I went to Winter Party in March and I tested Negative to the Swab test as well - I am doing all this because I am an only child with a Cuban Mother and only those who know will understand. A post shared by Jane Castro - JEI (@msjane38) on May 7, 2020 at 5:14pm PDT

Like thousands of others lining up for antibody tests around Florida — as of June 19, the state reported receiving more than 206,000 test results — Castro was looking for answers. Since March 14, she’d barely left her North Beach apartment, not an easy restriction for an extrovert who regularly performs at Miami Pride festivities and was a popular former cast member on VH1’s Tough Love Miami.

She missed regular visits with her elderly parents. A positive test would have eased her worries.

But epidemiologists say the tests are not so straightforward and warn that accuracy can vary depending on the prevalence of the disease where the test is administered.

“My worry is the nuanced interpretation,” said Andrew Azman, an epidemiologist with the Johns Hopkins Bloomberg School of Public Health, who co-authored a paper published in the journal Science Immunology last month explaining the best way to use the tests.

“People without training are just going to misinterpret it,” he said. “It’s not that they're stupid. It's just that understanding what the test results mean takes a little bit of time to understand.”

Even virologists and immunologists can misunderstand, he said.

“There’s just this huge divide,” he said. “Some of these ideas are very simple. Or simple to us. But we really wanted to try to hopefully break down some of these barriers between the two worlds.”

The messaging by the state, and the rapid increase in antibody testing, hasn’t helped clear up confusion. Gov. Ron DeSantis increased testing as part of his plans to reopen the state and said a positive antibody test could mean immunity.

“If you have the presence of antibodies, that means you've been infected with COVID-19,” he said in a press conference in early May in West Palm Beach. “And that's very important because the antibodies, most people believe, confer immunity at least. We don't know how long, but they're certain, some level of immunity.”

Testing services are readily available online. Quest Diagnostics, which has completed more than 115,000 of the state-reported tests, provides the service for $119.

Blood samples taken in Volusia County in May were tested for COVID-19 antibodies.
Credit AP
Blood samples taken in Volusia County in May were tested for COVID-19 antibodies.

“I saw that they were doing tests and it was free if you had insurance, and free if you didn't,” said Ryan Rea, who got sick in January with a high fever and cough and read about the tests at a walk-in clinic. “I checked every box.”

He lives in downtown Miami and works out of a WeWork shared office space, so was certain he could have been exposed. But at the time, diagnostic swab tests were hard to come by. He decided he was well enough to skip the test, reasoning that others needed it more.

Once the antibody tests became available, he made an appointment online at the MedRite Urgent Care clinic in North Beach, where Castro was also tested. After a half hour wait, he said a technician drew a vial of blood. Three days later he got the results: negative.

“At the risk of sounding like a conspiracy theorist, which I promise you I'm not, I don't actually put much stock in it,” Rea said. “I know very little about it. But I do know that there's such a high range of false positives and negatives.”

So why bother with the tests?

“It was more like I just wanted to know and since I'm also a nerd, I wanted to add my data as an individual,” he said. “What I can do is add my data to the pool and hopefully it'll help.”

Some local doctors have also rushed to provide testing. Banyan Medical Systems provided drive-up testing in several upscale Miami-Dade communities, including Bal Harbour, Bay Harbor, Surfside and Aventura, but came under fire for claiming they were using tests approved by the U.S. Federal Drug Administration. The FDA didn’t issue an emergency use authorization for the test, which has a different standard of review, until June 4.

This month, the sites closed. A notice on the company’s web site said “civil unrest” put its employees and contractors at risk. The company declined an interview request by WLRN.

Quest, which has performed about 63 percent of the tests reported by Florida, also declined to comment. A spokeswoman initially said she would provide information on background, but when asked for on-the-record responses, did not respond.

When Hialeah was looking to test its city employees, Dr. Marlow Hernandez, CEO of Cano Health, offered to handle the testing. He said while he warns people to continue practicing social distancing and other measures, he believes antibody testing can help patients understand their risks.

Earlier in the year, with a shortage of diagnostic tests, he said looking for antibodies helped doctors decide if they needed to order diagnostic tests — which are harder to come by.

“So putting all that together — the surveillance element, the acuity of illness and the necessary comfort in these troubling times — is why it was important for us to go out there and do these tests,” he said.

And if someone tests positive?

“I would tell them that as far as we know from the cases that we've studied, you are likely immune,” he said.

While it’s not clear how long immunity lasts, Hernandez said he believes the results can help reassure patients.

Gov. Ron DeSantis previously hinted that a positive antibody test could mean immunity but experts say the findings are not that simple.
Credit MATIAS J. OCNER / Miami Herald
Miami Herald
Gov. Ron DeSantis previously hinted that a positive antibody test could mean immunity but experts say the findings are not that simple.

“Even when somebody tests positive for the antibody, we're not telling them, ‘OK, take off your mask. You have nothing to worry about,’” he said. “We're saying 'Oh, great news. You may be protected. Continue to use your mask. Continue to have all the precautions and wash your hands and say, you have something that I would like to have.’”

But health experts worry the risk of misunderstanding test results are too high for a test that is essentially meaningless outside of a controlled study.

“There is likely to be some degree of what we call risk compensation, where somebody believes that they are protected and then they may take extra risks that they wouldn't otherwise take,” Azman said.

In its guidance for how to use antibody testing, the Centers for Disease Control and Prevention warns that in areas with few cases of the disease, the likelihood of a false positive is higher. Because of that uncertainty, the American Medical Association does not recommend antibody testing for individual use.

“If this virus acts like other viruses, we may have immunity. But at this point, we just don't know,” AMA President Dr. Patrice Harris told WLRN. “So if anybody has any questions or has received an antibody test thus far, we urge them to talk to their physician because some of the antibody tests have been approved by the FDA for emergency use. Many have not. And so we want everyone to know that.”

Carlos Domingo is a computer scientist with a business degree from Stanford. He suspected that he and his wife might have been exposed even though they never had symptoms because he travels frequently. He has an office in Tokyo, traveled to New York twice in March and welcomed family from Spain. With three kids under seven, the couple worried about getting sick and not being able to care for their children.

“If I had been exposed and [had] it in an symptomatic way, then I could be, you know, less worried about getting it later,” he said. “I'm not that worried about myself getting the coronavirus. I'm much more worried about the implications at home.”

In early May, he and his wife were tested at a pharmacy near their Key Biscayne home. He said the staff at the pharmacy assured him the test was accurate. But when he reported the negative results on social media, many commenters warned him the testing could be inaccurate. Despite the uncertainty about immunity, Domingo said a positive result would have provided him with some measure of comfort.

“It certainly seems to be the case that there's some immunity that you get, at least for the first few months, if you test positive for antibodies. I was hoping for that,” he said.

That doesn’t mean he would have stopped avoiding crowded places, wearing a mask or following any other guidelines. But after months at home with four-year-old twins and a 7-year-old, Domingo said he and his wife decided the kids needed to start reconnecting to the outside world. So they’re forming what he calls a ‘trust circle’ with friends and other parents who have taken precautions.

“Otherwise they're just going to go crazy staying at home for two months,” he said. “It's quite a toll to be here for three months, doing Zoom calls with our friends and not be able to actually see anyone.”

The urge to get tested and get more information is understandable, Azman said. His brother and sister-in-law, a doctor in New York City, told him they planned to get tested. 

"And she understands this stuff somewhat," he said.  “A lot of people, they sort of get it, that it's not meaningful. But you’re like, well if it’s positive that will give me some hint to understand if that cold I had last week was really COVID.  I think In these times of great uncertainty, everyone wants to see a little bit of light.”

Copyright 2020 WLRN 91.3 FM. To see more, visit WLRN 91.3 FM.

Jenny Staletovich has been a journalist working in Florida for nearly 20 years.