Updated: Apr 16
Many people exposed to the novel coronavirus will have little or no symptoms. Testing for the presence of the antibodies is important to identify persons who have already been exposed. Antibodies appear shortly after exposure to help fight the virus and can remain in the blood for months to even years after illness.
IgM is the first antibody to appear after the virus enters through the nose or mouth. IgM can be seen within 7-8 days after exposure and is associated with active disease. IgM is detectable in the blood until around days 19-21 of illness. IgG appears within two weeks and is the antibody associated with long-term immunity.
With some virus strains, long-term immunity may occur once these antibodies are produced. At present, there is not enough data to say with certainty if IgG produced to fight this strain of coronavirus will provide similar long-term protection. For this reason, we recommend that you should continue to follow CDC and local government guidelines regardless of a positive Covid-19 antibody test.