Your Coronavirus Antibodies Are Disappearing. Should You Care?

Your Coronavirus Antibodies Are Disappearing. Should You Care?

Declining antibody levels do not mean less immunity, experts say. Besides, two widely used tests may detect the wrong antibodies.

A pharmacist administering a test for coronavirus antibodies in France last week. Credit...Frederick Florin/Agence France-Presse “” Getty ImagesJuly 26, 2020, 5:00 a.m. ET

Your blood carries the memory of every pathogen you've ever encountered. If you've been infected with the coronavirus, your body most likely remembers that, too.

Antibodies are the legacy of that encounter. Why, then, have so many people stricken by the virus discovered that they don't seem to have antibodies?

Blame the tests.

Most commercial antibody tests offer crude yes-no answers. The tests are notorious for delivering false positives “” results indicating that someone has antibodies when he or she does not.

But the volume of coronavirus antibodies drops sharply once the acute illness ends. Now it is increasingly clear that these tests may also produce false-negative results, missing antibodies to the coronavirus that are present at low levels.

Moreover, some tests “” including those made by Abbott and Roche and offered by Quest Labs and LabCorp “” are designed to detect a subtype of antibodies that doesn't confer immunity and may wane even faster than the kind that can destroy the virus.

What that means