The viruses that cause influenza—the flu—change each year, making it more difficult for our immune systems to recognize and eliminate them. This, in turn, allows the flu to infect millions of people every year, causing pneumonia and other severe complications that can lead to hospitalization and death. Our best defense against the flu is to get the annual vaccination.
The flu vaccine is adjusted each year to adapt to the changes in the virus, which is why we have to get vaccinated every year. No tolerance develops to flu vaccination, so it continues to help every year.
Many patients believe that flu shots can cause the flu. However, patients who get sick after receiving the flu shot were already becoming ill at the time of their flu shot and simply did not know it yet. Controlled trials have proven conclusively that flu shots help prevent the flu and don’t cause it.