Factsheet: Do Vaccines Overwhelm the Immune System?

Factsheet explains what an antigen is and dispels the myth that vaccines overwhelm the immune system. Antigens are the parts of viruses and bacteria that induce immune responses, and introducing antigens to the body through vaccines can protect people if they are exposed to the virus or bacteria in the future. The factsheet also notes that the number of antigens present in routine childhood vaccines has decreased throughout history.