This particular flu has affected younger people disproportionately in the population. Their more vigorous immune systems make them more vulnerable. I know it seems counterintuitive. But that is the reason for the shift in focus on immunization of younger rather than older people.
Swine Flu Vaccine on Track for Fall: CDC: MedlinePlus
"Unlike seasonal flu, the H1N1 flu continues to pose more problems for younger people, Schuchat added. 'There are a higher attack rates and hospitalizations in younger adults and children,"'she said.
In the Southern Hemisphere, where the winter flu season is under way, cases of H1N1 virus infection are being reported, along with cases of seasonal flu, Schuchat said. 'In the reports we have, the virus continues to affect generally younger people, sparing the elderly to a great extent,' she said.
And, as in the United States, the H1N1 virus is causing severe respiratory problems in the Southern Hemisphere, a trend that's unique to the new strain of flu and not seen in seasonal flu, Schuchat noted. 'We've heard of intensive-care units with many younger people who have this new H1N1 virus.'
Last month, researchers reported in the
New England Journal of Medicine that, unlike seasonal flu, the new H1N1 flu strain attacks younger people and can be more severe and deadly in that group."