Positive test result: Indicates potential previous exposure to the virus that causes COVID-19 resulting in the development of specific viral antibodies, regardless of whether you experienced COVID-19 symptoms. It does not confirm infection or immunity. It is unknown whether the presence of COVID-19 antibodies will provide immunity to future infection and individuals should continue to follow all COVID-19 safety guidelines provided by the CDC. As with all tests, false positives, or a test result that incorrectly states the presence of antibodies, can occur. If your test result is positive, the Red Cross may contact you to request additional information and conduct further testing as part of a research study.
Negative test result: Indicates that you probably have not been exposed to COVID-19 and therefore have not developed antibodies to the virus. It also could indicate that antibodies are present but at levels below the test’s threshold for detection, or that the test did not recognize those antibodies. It is possible that you can still contract the virus, if exposed. It takes one to three weeks after an infection for antibodies to be detectable.
Inconsistent test result: Indicates that your initial antibody test was reactive for COVID-19 antibodies, while your secondary test came back negative for COVID-19 antibodies. As with all tests, false positives, or a test result that incorrectly states the presence of antibodies, can occur. Alternatively, the level of COVID-19 antibodies may be too low to be detected by the second test.
One reason a donor may have an inconsistent test result is that they received a COVID-19 vaccine. This is because the initial and secondary antibody test target different parts of the COVID-19 virus. It is possible that the initial antibody test used detected the presence of antibodies to one viral region (the same one used in the vaccine), while the secondary test (targeting a different region of the virus), was negative.
Not Available test result: While rare, some donations may not be able to be tested due to processing issues. Donors will need to have a successful donation to receive COVID-19 antibody results. Per standard procedures, only successful donations are sent to our laboratory for testing.
Pending test result: Indicates that the test is still in process. Donors can expect to receive the results of their antibody test within one to two weeks through our Red Cross Blood Donor app or online donor portal.