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Explainer: What Are Antibodies?

Get three fast facts about antibodies, which play an essential role in the immune system and help fight infections.

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illustration of Y-shaped antibodies

COVID-19 made antibodies a hot topic. Did people infected with COVID-19 have antibodies to the virus? And did people who received a vaccine make antibodies that could protect them from serious symptoms?

Having antibodies to SARS-CoV-2, the virus that causes COVID-19, was an important piece of the puzzle. It’s the same scientific reasoning behind other vaccines, such as those given in childhood to prevent measles or polio. The vaccine introduces a dead or weakened portion of the germ – enough to prompt the body’s immune response and the creation of antibodies – without giving the person the disease itself.

Here are three fact facts about antibodies:

  1. Antibodies, also known as immunoglobulin, are Y-shaped molecules that enable your body to “remember” a bacteria or virus and disarm it before it can make you sick. Antibodies attach themselves to the invading germ and prevent it from getting into your cells.
  2. There’s more than just one kind of antibody: IgG, IgA, IgM, IgD and IgE. (Ig means “immunoglobulin.”) Each class has a different structure and a slightly different function.
  3. Antibodies aren’t the whole story. Antibodies are part of the adaptive immune system, which also includes T cells and B cells. Research into COVID-19 has shown that T cells appear to play an important role because of their ability to mount a defense against virus variants.

Learn more about T cells.

Read: What Is Immunoglobulin?