The Red Cross is using the Ortho Clinical Diagnostics VITROS Anti-SARS-CoV2 Total Test. This test is available through FDA Emergency Use Authorization and measures total antibodies. According to Ortho Clinical Diagnostics, their test reports a sensitivity of 90% and a specificity of 100%.
As with all tests, false positives, or a test result that incorrectly states the presence of antibodies, can occur. On Sept. 21, the Red Cross began secondary testing of donations that come back positive to confirm COVID-19 antibody test results for donors.