Skip to main content

Explainer: What Are Antibodies?

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

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.

Understanding Antibodies

Want to know why antibodies are so important to the immune system? Here are three fact facts about antibodies:

  1. What are antibodies? 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. Are there different types of antibodies? There are several types of antibodies: IgG, IgA, IgM, IgD and IgE. (Ig means “immunoglobulin.”) Each class has a different structure and a slightly different function.
  3. Are antibodies part of the innate or adaptive immune system? Antibodies are part of the adaptive immune system, but they're not the whole story. The adaptive immune system 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 in this explainer article.