Antibodies are proteins that are produced by the immune system to fight off a specific infection and protect against reinfection. When someone becomes infected with COVID-19, the immune system releases antibodies that bind to antigens to help eliminate the pathogen.

There are 5 different kinds of antibodies found in the body and each plays it's own unique role in immunity. The antibody test looks for the presence of two specific antibodies that help to identify if a person has recently been in contact with COVID-19.

IgM antibodies are often present within 3 to 5 days after incubation and may indicate an active or recent infection with COVID-19. IgG antibodies develop later following infection, and generally do not begin to appear until 7 – 10 days after infection. IgM antibodies clear the body before IgG antibodies. IgG antibodies decline over time after an infection has been cleared.