Why do we suffer repeatedly from influenza. Why does active immune response fail to protect us from influenza?
As the influenza virus can evolve rapidly due to the genetic mutation of the virus so the active immunity response fail to protect us from influenza and it relapses again and again in human body. Active immune response are of 2 types natural acquired active immune response and artificial active immune response or immunization. The natural acquired active immune response occurs when the person is exposed to a live pathogen that develops disease and becomes immune by producing a specific antibody against the specific antigen or virus, so that if the specific virus or antigen again attack the body then it will unable to produce disease because the antibody against that disease is already present from early due to the previous exposure to that particular pathogen or the presence of primary immune response.artificial active immune response or immunization is a phenomenon to induce a substance that contains the antigen or half killed pathogen into the body to form specific antibody against it.
As the influenza virus evolves rapidly because of its genetic mutation, so the body which produce a specific antibody during the previous exposure to the virus will not work out during the next time exposure to the virus as the virus is evolved and seems to be a new virus for the body. So active immune response fail to protect us from influenza.