There are three different types of antibodies: IgM, IgG, and IgA.
- Immunoglobulin M (IgM) is usually produced as the body’s first response to an infection. However, for COVID-19, IgM antibodies are produced around the same time as IgG antibodies. Generally, IgM may provide short-term protection and can help tell if an individual has been recently infected.
- Immunoglobulin G (IgG) is the most common type of antibody. It’s usually made several days to weeks after most infections. However, for COVID-19, IgG antibodies are produced around the same time as IgM antibodies. Generally, IgG remains in the body and may provide long-term protection against future exposure.
- Immunoglobulin A (IgA) is found in the blood, sinuses, lungs, and stomach. Generally, IgA helps protect these areas from infection. However, it’s unknown what role these antibodies play in determining exposure or immunity to COVID-19.
There is not enough evidence at this time to suggest that people who have these antibodies are protected against future COVID-19 infections. Additionally, antibody testing by itself should not be used to establish the presence or absence of COVID-19 infection or reinfection. Visit the CDC website for further information.