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There Are Many Reasons to Be Wary of Antibody Tests
What to know about getting tested for immunity
Antibody tests for Covid-19 are becoming widely available across the United States. Some companies, like Quest Diagnostics, even offer at-home kits. Whether you take one in a doctor’s office or your bedroom, an antibody test can, ideally, determine whether you’ve previously been infected with Covid-19. It does so by searching your blood for antibodies, which are proteins the immune system makes when it encounters the coronavirus.
While it’s likely people develop some immunity after being infected with the coronavirus, experts still don’t know whether you need a certain amount of antibodies to fight off another infection. And even if you do have the right amount, it also isn’t clear yet how long its protection lasts. (The pandemic was only officially declared on March 11, so there hasn’t been time to study long-term immunity yet.)
If you’ve felt even remotely sick in the past few months, just knowing whether you ever had Covid-19 could be a welcome relief. But there’s one big problem: These tests can be so inaccurate that they might not tell you anything meaningful.
Guidance updated this week by the U.S. Centers for Disease Control and Prevention (CDC) states that antibody tests are useful for determining the proportion of people in a population that have been sick before, as well as other patterns of disease spread. It also says that the tests should not be used to determine whether a person is immune.
As the first tests began appearing as early as late February, scientists raised concerns about their accuracy, which varied widely — too widely for the tests to be useful in making decisions about personal health. The same holds true today, though the accuracy of some new tests is more promising than others. In May, the FDA began pulling antibody tests from the market after updating its guidelines to weed out products making fraudulent claims.
Here’s the latest on what we know about antibody tests and what we’re still waiting to find out.
Just because you have antibodies doesn’t mean you’re protected from Covid-19, so following social distancing and…
