A substance added to a flu vaccine to increase the immune response to the vaccine.
A protein located on the surface of an influenza virus that can cause your body to create an immune response. All flu vaccines contain antigens, which trigger an immune response to influenza.
An ongoing process that involves small changes in influenza virus genes, which can cause changes to the two antigens on the surface of the virus. Antigenic drift can cause flu viruses’ antigens to change so much that a person’s immune system might not recognize them, making that person susceptible to the flu.
Another way to describe live flu viruses that are weakened. This term may be used to discuss the use of flu viruses in nasal spray vaccine development.