Researchers Report on Study of of H1N1 Virus in Milwaukee

How severe is the H1N1 influenza?

And why were there so many cases in Milwaukee this spring and summer?

"The hardest and, globally, the most important question, is the severity," said Marc Lipsitch, a professor of epidemiology and director of the Harvard School of Public Health's Center for Communicable Disease Dynamics.

Lipsitch, who is leading the Harvard study of Milwaukee and a handful of other communities around the nation, said it may be difficult to quickly pinpoint the virulence of swine flu. Researchers hope to know enough about the virus to prepare rough estimates for a fall outbreak, including what fraction of the infected will need to be hospitalized; what fraction will need to be treated in intensive care units; and what fraction will die.