Ferreting out swine flu - virus causes slightly more severe disease than seasonal flu

The swine flu pandemic is well under way. With the WHO citing almost 60,000 laboratory-confirmed cases at the time of writing, the race is truly on to understand more about the virus. Now, two new studies have painted a fresh but partly contradictory picture about two of the virus's most important aspects - its infectivity (its ability to spread from host to host) and its virulence (its ability to cause disease in a host). These two traits will largely determine the threat that the virus poses, especially in relation to more familiar garden varieties of seasonal flu.