Autoimmune diseases occur when the body reacts against itself. Some diseases characterized by this type of reaction include Guillain-Barre Syndrome (GBS), multiple sclerosis, and diabetes. Autoimmunity can be induced by genetic predispositions. But, sometimes bacterial or viral infections can cause autoimmune diseases. For example, campylobacter, an intestinal bacterial infection, can cause GBS, a disease of the peripheral nervous system. Influenza virus can exacerbate symptoms of multiple sclerosis, a disease of the central nervous system. And Coxsackie virus can cause diabetes, a disease that occurs when the body reacts against cells in the pancreas that make insulin. Because natural infections can lead to autoimmune conditions, people can reasonably wonder whether vaccines can also cause autoimmunity as well.
Numerous studies have examined many different vaccines. To date, none have consistently been shown to cause autoimmune diseases. In some studies influenza vaccine was shown to cause GBS at a rate of one case per million vaccine recipients. But, this should be viewed in light of the fact that natural influenza infection causes GBS in 17 per million people infected. So, in a sense, influenza vaccine could be viewed as preventing a more common cause of GBS.
The notion that vaccines don’t cause autoimmunity makes sense. Since vaccines don't drive the immune response nearly as vigorously as natural infections do, it is less likely that they would induce autoimmunity. However, scientists continue to study questions related to vaccines as a cause of autoimmunity as they arise.
The following autoimmune diseases are addressed in more detail on dedicated pages: