Vanderbilt University Medical Center is leading a multicenter national study to evaluate the effectiveness of the influenza vaccine for preventing the flu’s most serious side effects — admission to an intensive care unit (ICU), organ failure and death.

An influenza diagnosis for people 65 and older is serious. Up to 85 percent of influenza-related deaths occur in older adults, the Centers for Disease Control (CDC) and Prevention reports.

High-dose influenza vaccine is 24 percent more effective than the standard-dose vaccine in protecting persons ages 65 and over against influenza illness and its complications.

Research in the last two years to examine the effectiveness of the influenza vaccine has raised public doubt about the flu shot's effectiveness. But two Vanderbilt researchers co-wrote an editorial in the Journal of the American Medical Association (JAMA) recently to help balance the current debate.