Experts warn that it is not yet known if the presence of COVID-19 antibodies means that a person is immune to the virus

By Julie Mazziotta
April 29, 2020 02:02 PM
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As states and cities around the U.S. look to reopen — and several partially have — health experts say that the first step is expanding testing to identify who currently has the new coronavirus, COVID-19, and how much of a population has already had the virus.

There are two types of tests, and each has a different purpose. Diagnostic testing, conducted with a nasal swab, shows who is currently contagious and should be put in isolation. And antibody testing, a blood test that can identify COVID-19 antibodies, will help to understand how many people have had the virus, even if they never showed symptoms.

Antibody testing is now being touted as the best hope for resuming normal life while the world waits for a COVID-19 vaccine, because the presence of antibodies hopefully means that a person is now immune to the virus. There are now over 150 antibody tests on the market, and doctor’s offices and private labs are offering them to Americans — at a price.

“Testing for antibodies will allow us to determine how many individuals were exposed to the virus, how many individuals have produced antibodies to the virus and are people with antibodies protected from getting the virus again,” Dr. Joan Cangiarella, the vicechair of clinical operations in the Department of Pathology at NYU Langone Health, tells PEOPLE. “By showing who doesn’t have the antibodies it can show who still remains vulnerable to getting the virus.”

But Cangiarella and other experts warn that the available antibody tests may not be the golden ticket. On Thursday, the World Health Organization put out a brief warning that there is no evidence yet that having COVID-19 antibodies means that a person is immune from getting it again.

“Right now, we don’t understand enough what it means for a person to have antibodies,” says Cangiarella. “The presence of antibodies does not equate with immunity.”

The other issue is that the tests on the market are not fully accurate. The Food and Drug Administration has granted emergency approval to the makers of most of these tests without actually reviewing them, due to the current circumstances.

“Each of these are in various stages of emergency use authorization and haven’t been vetted by the FDA because they haven’t had the time,” Dr. Alan Wu, professor of Laboratory Science at the University of California, San Francisco and the laboratory director at San Francisco General Hospital, tells PEOPLE.

Instead, the FDA has formally approved just eight antibody tests, NBC News reported.

“It’s buyer beware for most of them,” says Wu.

Wu and his team conducted their own review of ten different antibody tests, and found that the degree of accuracy varied from 80 to 100 percent.

Many of the tests have been brought to the market too soon, says Cangiarella.

“Some have poor sensitivity, not detecting antibodies, others producing false positives, indicating that you have antibodies when you don’t.”

Wu says that people can go forward with antibody testing, and he sees it as helpful for research purposes, but that the testing needs to be “accompanied by education.”

“There can’t be a misconception of what the results are telling you, because that can be a bad outcome for the individual,” he says. “Certainly if the test is negative, that would lead one to think that they are susceptible and would need to be highly cautious of their activities moving forward. But those who are positive may have this false sense of security that they’re immune from future infections when in fact they’re not.”

“More studies need to be undertaken before we understand what having antibodies means,” adds Cangiarella.

Both Wu and Cangiarella say that if states want to pull back stay at home orders, Americans need to continue social distancing and improve testing of all kinds.

“I do think that it will be important to test more individuals so that we can detect asymptomatic positive patients, those who may be able to spread the virus unknowingly,” she says. “We also need to establish a better system of contact tracing so as to quarantine those that may have been exposed to the virus. And we need to see that hospitals aren’t overwhelmed and the numbers of admitted patients with COVID is decreasing.”

And Wu says a “better generation of an antibody test” — one that can identify the amount of antibodies a person has and how those antibodies will react with a vaccine — is necessary, and something that he and others are working on.

“Now that the curve is flattening just a little bit, we can start to devote our attention to improving what we’re doing and develop better assets,” he says.

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