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CBS13 Investigates: Putting The Antibody Test To The Test

SACRAMENTO (CBS13) — Over the past few months, antibody tests flooded the market promising to answer the nagging question: could you be immune and protected from COVID-19?

By now, you've likely heard some of those tests can be inaccurate, so is it still worth getting one?

After getting sick in mid-March, investigative producer Michele Youngerman from CBS Chicago decided to get not one, but three COVID-19 antibody tests to see if she actually had the virus, and put the tests to the test.

Of the 250 antibody tests on the market, a little over 20 had been given temporary approval by the FDA. Michelle tested three of them and got three different results two months after she was sick.

The first was a blood test that came back positive for antibodies from an older COVID-19 infection. She then tried a rapid finger prick test which came back positive for antibodies from a recent infection. A second blood test was negative for all antibodies.

So, did she have COVID-19?

Infectious disease expert Dr. Phillip Norris says, while there are certainly concerns about test accuracy, even accurate tests may not accurately predict if you actually had coronavirus or if you may now be immune.

"So it's possible she had weak antibodies or a false-positive test," Dr. Norris said. "We're finding in people with mild infection, they develop lower-level antibodies, and those antibodies fade."

He points to a study out of China that suggests they may fade by 70% over the first few months.

"Does that mean that if you have low-level antibodies that you wouldn't necessarily be protected from getting COVID again?" we asked Dr. Norris.

"Well, that's certainly what we suspect," Norris said.

He says that's an active area of research, but what they do know is that coronaviruses, in general, don't induce great antibody responses.

"So we would be surprised if someone were protected for more than a year or two. And in most cases, we think the protection may only last a few months," Norris said.

He says the hope right now is that even with weak antibodies, a second COVID-19 infection would be milder than the first, and the same is true for a vaccine.

"A vaccine may not protect from infection but may protect from severe disease," he said.

In the meantime, it's important to know that even a positive antibody test might not actually be positive. At least 46 antibody tests were pulled from the market in just three months.

So is it worth getting a test? Dr. Norris says, sure, if it's just about the curiosity factor. However he stressed that the results should not change your behavior. Masks and social distance are crucial to help prevent the spread of the disease because even if you test positive for antibodies today, you might test negative a month from now.

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