Diminished immune responses with aging predispose older adults to common and uncommon influenza complications

•Older adults have preexisting vulnerability to flu infection and its complications.•Weakened and delayed immune responses lead to increased systemic inflammation.•Dysregulated immune responses and inflammation leads to multiorgan complications.•Vaccination reduces severity and duration of flu complications in older adults.•Older adults need closer monitoring for flu complications to prevent morbidities.