Why Do We Need Antibody Testing?

We spoke with Kells McPhillips of WELL + GOOD about COVID-19 antibody tests.

When the antibody tests were rolled out in early April, their purpose was to identify those who has already been exposed to the virus. Rather than test for the actual virus, the blood test recognizes antibodies, or proteins produced by white blood cells as a response to the coronavirus.

Knowing who had already contracted the virus is hard, especially because 25% of individuals are asymptomatic and 80% of cases are mild. Getting a full picture of who has truly had the virus is a big deal, especially because it means they may be immune to it in the future.

What would knowing this information do?

“If we can identify that they’ve already inoculated the virus, and are therefore [potentially] immune, then [the fear of getting sick] doesn’t have to add stress to everything else is going on,” Dr. Rand McClain, chief medical officer of Live Cell Research, said. “We can put those people on the front lines, and those who don’t have the antibodies we can choose to be more careful with.”

Which Tests Are Accurate?

On the surface, the presence of antibody testing only seems to be a positive. But unfortunately, not all of the tests are delivering results. A large quantity of masks ordered in the UK turned out not to be able to test for the virus. The University of Washington also had some issues when the tests they ordered from China had to be called due to bacterial contamination.

How do you know if the test is safe? Only use from specific FDA-approved providers. Those approved tests are both sensitive and specific. They can detect a “true positive” to this specific strain of virus. Using the wrong test is not only inaccurate but dangerous.

“This can be potentially extremely dangerous,” says George Declos, MD, PhD, respiratory disease and occupational medicine specialist at the University of Texas. “Not only because [a bad test] gives misinformation, but because it may trigger actions on the part of employers, and possibly even health-care providers, to act on the basis of a positive result that is inaccurate.” For example, if someone goes back to work after getting a false positive from a bad antibody test, Dr. Declos says, they’re now being put in a dangerous situation where they could actually get infected (because no antibodies = no immunity at all.)

Emergency Authorizations

Even though risks are involved, there isn’t a whole lot of oversight right now. The FDA issued emergency use authorizations (“EAUs”) for four COVID-19 antibody tests earlier in the month. The Secretary of Health and Human Services issued a policy stating “circumstances exist justifying the authorization of emergency use of in vitro diagnostics for the detection and/or diagnosis of the novel coronavirus.” What does this mean?

A company avoids getting vetted as long as they write a letter to the FDA promising to adhere to the rigorous requirements of the tests. Dr. McClain believes that a lot of companies are following through on their promise. Though there are still a number of others who have not submitted letters or are falsely advertising that they are “approved by the FDA”.

“They are registering with the FDA through a letter saying, ‘We promise you the tests have been validated.’ So if it does come out that they’re not, in fact, validating this testing, they’re going to get a pretty good spanking,” he says.

This means you can’t trust these tests in the same way you’d trust tests from a FDA-vetted laboratory. Currently though, the FDA, Center for Disease Control and Prevention (CDC), and National Institutes of Health (NIH) are looking into and warning companies with illegitimate tests.

My Workplace Is Offering An Antibody Test

Both Dr. Declos and Dr. McClain agree that we are not at a place to end the remote status of workers, even with antibody tests.

“If you are thinking about having people to return to work based on an assumption that just because they have antibodies means that they are protected from infections, and it turns out not to be the case when the science is reviewed, that is concerning because you’re putting people in harm’s way unnecessarily,” says Dr. Declos. “I think antibody testing is a good thing, but I think jumping the gun and making use of testing before the science is there can be extremely dangerous.”

Say you do get your hands on a test, how can you find out if it’s legitimate? “If I’m the patient, that’s the best way. A doctor is supposed to go through this process and vet [the test], and has the tools, presumably, to do so,” says Dr. McClain. The FDA’s website is a good resource as well. They keep a current list of tests and their status. Be weary of cheap tests as well.

What’s Next?

A $484 billion relief bill in Congress would give more funding to COVID-19 testing. With more testing, we’d have a larger sample size of those who have received legitimate antibody tests.

“A large amount of testing would be required to get a handle on this virus,” says Dr. McClain. “We need a representative sample in this country to figure out a range of how many people are infected, how many people have symptoms and don’t, and how many have died. Right now, we have what would be considered a very biased sample in that we really only have information on the people we know are infected, and particularly those with severe disease.”

Dr. Rand believes with more data comes more informed decisions about opening back up.

“All this information is still not sufficient to get our arms around the virus. We have statistics which tell us that fewer people are dying now. About the virus itself, though, we know very, very little still, because we don’t know how many people are infected now.”

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