coronavirus antibody testing

Tests for the immune response to the coronavirus are revealing thousands of people who were infected but never got severely ill. The findings suggest the virus is less deadly than it first appeared.

As more and more people get tested for antibodies to the coronavirus, infectious disease specialists worry that those tested — and their employers — may not understand the limits of the results.

Antibody tests can identify people who have been previously exposed to the coronavirus. But false positive results are a concern. Performing two different tests could reduce errors.

An antigen test could be quick, and much simpler and cheaper than the PCR tests now used to spot people infected with the novel coronavirus. But some scientists worry about an antigen test's accuracy.