A new study is providing insights into the 2009 swine flu epidemic, and why more serious complications arose in healthy middle-aged people than expected. The researchers say the culprit may be antibodies to seasonal flu found in the seriously ill patients, which might have caused an immune system overreaction in the lungs.
"Nobody really had a good explanation for why middle-aged people seemed to have more severe disease than would have been expected," says Richard Scheuermann, an immunologist at the University of Texas Southwestern Medical Center in Dallas. "This explanation is the first one that I've seen that actually makes sense." [Nature News]
Normally, severe flu illness happens in the very young (who haven't been previously exposed to the flu and don't have protective immunity) and the elderly (who have weakened immune systems). Instead of affecting these groups, the 2009 pandemic H1N1 "swine flu" primarily caused severe reactions in middle-aged ...
