Pandemic H1N1 influenza caused a 15-fold increase in admissions to intensive-care units for lung problems in Australia and New Zealand during the winter flu season, researchers reported in the New England Journal of Medicine, offering a taste of what might be expected in the U.S. this winter. In a separate study, U.S. researchers reported that one-quarter of Americans who were hospitalized with influenza symptoms last spring ended up in the intensive-care ward and 7% died. Both groups of researchers concluded that H1N1 flu was slightly more dangerous than seasonal flu.