"Canadian doctors probing the worst cases of swine flu in Canada have made a striking finding: 40-year-olds, many previously healthy, appear most at risk of developing severe H1N1 disease.

The finding is based on global reports of illness and case reports from critically ill patients in intensive care units across the country. The investigation confirms the virus behind the first flu pandemic of the 21st century does not fit the typical patterns of influenza.

Significant, doctors say, is its ability to cause serious disease in previously healthy people."

http://www.canada.com/health/Swine+hits+healthy+year+olds+hardest/1935107/story.html