COVID-19 antibody tests

COVID-19 antibody tests detect antibodies—proteins produced by your immune system—in your blood, indicating you have been exposed to the virus in the past. These tests help determine if you’ve developed an immune response after infection or vaccination. A positive result suggests prior exposure, but it doesn't confirm current infection or immunity strength. The accuracy depends on timing, as antibodies take time to develop after infection. Antibody tests are useful for understanding population exposure and immune response but are not definitive for diagnosing active COVID-19 cases.