How effective is the flu shot?

The flu vaccine has been determined to be effective in preventing influenza in about 70% - 90% of healthy people under the age of 65 and is your best method of protection. Among elderly persons not living in chronic-care facilities and people with long-term medical conditions, the flu shot is 30%-70% effective in preventing hospitalization for pneumonia and influenza. Among elderly nursing home residents, the flu shot is most effective in preventing severe illness, secondary complications, and deaths related to the flu. In this population, the shot can be 50%-60% effective in preventing hospitalization or pneumonia and 80% effective in preventing death from the flu.