The Centers for Disease Control and Prevention's Morbidity and Mortality Weekly Report found U.S. adults ages 18 to 64 represented 61 percent of all hospitalizations from influenza -- up from the previous three seasons when this age group represented only about 35 percent of all such hospitalizations.
Influenza deaths this season are following a pattern a similar to the pandemic in 2009, which involved the same virus strain H1N1. People ages 25 to 64 accounted for about 60 percent of flu deaths this season compared with 18 percent, 30 percent, and 47 percent for the three previous seasons, respectively, the report said.
During 2009/2010 flu season, people 25 to 64 accounted for an estimated 63 percent of deaths.
In a typical flu season, seniors and the elderly ages 65 and older usually account for the most deaths and hospitalizations.
"Flu hospitalizations and deaths in people younger- and middle-aged adults is a sad and difficult reminder that flu can be serious for anyone, not just the very young and old; and that everyone should be vaccinated," Dr. Tom Frieden, director of the CDC, said in a statement. "The good news is that this season's vaccine is doing its job, protecting people across all age groups."