To conduct an antibody test for COVID-19, typically a health care professional takes a blood sample, usually by a finger prick or by drawing blood from a vein in your arm. Then the sample is tested in a lab to determine whether you've developed antibodies against the COVID-19 virus.
Both SARS-CoV-2 IgM and IgG antibodies may be detected around the same time after infection. However, while IgM is most useful for determining recent infection, it usually becomes undetectable weeks to months following infection; in contrast, IgG is usually detectable for longer periods.
Diagnostic tests can show if you have an active COVID-19 infection. Antibody or serology tests look for antibodies in a blood sample to determine if an individual has had a past infection with the virus that causes COVID-19 but cannot be used to diagnose current COVID-19 infection.
Antibody tests for COVID-19 are available through healthcare providers and laboratories. Check with your healthcare provider to see if they offer antibody tests and whether you should get one.
IgG antibodies to SARS-CoV-2 are generally detectable in blood several days after initial infection, although the duration of time antibodies are present post-infection is not well characterized. Individuals may have detectable virus present for several weeks following seroconversion.
Be aware that a positive result from an antibody test does not mean you have a specific amount of immunity or protection from SARS-CoV-2 infection. If you have a positive test result on a SARS-CoV-2 antibody test, it means that it is possible you were previously infected with the SARS-CoV-2 virus.
“PCR tests are more reliable and accurate due to testing the specific genetic material of the virus, eliminating the interference from other viruses,” said Heather Seyko, a Laboratory Services manager for OSF HealthCare.
Viral Test TypesLaboratory tests can take days to complete and include RT-“PCR” tests and other types of nucleic acid amplification tests (NAATs).Rapid Point-of-Care tests can be performed in minutes and can include antigen tests, some NAATs, and other tests.
PCR tests are more accurate than antigen tests. "PCR tests are the gold standard for detecting SARS-CoV-2," says Dr. Broadhurst. "It is the most accurate testing modality that we have.
"Antibodies can last in your blood for months, but we don't know how much you need to be protected", said Horovitz, who was not involved in the new study. People who had more severe COVID-19 disease do have higher antibody levels but that doesn't protect them forever, he noted.
At this time, it is unknown for how long antibodies persist following infection and if the presence of antibodies confers protective immunity.
Antibody Testing Is Not Currently Recommended to Assess Immunity After COVID-19 Vaccination: FDA Safety Communication | FDA.
The Assure COVID-19 IgG/IgM Rapid Test Device should not be used to diagnose acute SARS-CoV-2 infection.
The VITROS Anti-SARS-CoV-2 Total N Antibody test is intended for use as an aid in identifying individuals with an adaptive immune response to SARS-CoV-2, indicating recent or prior infection.
In the United States, there are three anti-SARS-CoV-2 monoclonal antibody treatments with FDA Emergency Use Authorization (EUA) for the treatment of COVID-19: bamlanivimab plus etesevimab, casirivimab plus imdevimab,, and sotrovimab.
Currently authorized SARS-CoV-2 antibody tests have not been evaluated to assess the level of protection provided by an immune response to COVID-19 vaccination. If antibody test results are interpreted incorrectly, there is a potential risk that people may take fewer precautions against SARS-CoV-2 exposure.