What if Swine Flu Meets Bird Flu?

Among the scarier prospects for the future of swine flu, which has reached pandemic status but killed relatively few people, is that it mixes with bird flu to form a lethal hybrid. Jokes about flying pigs aside, a mix of the easily spreadable H1N1 and the especially virulent bird flu is "a nightmare vision" for scientists, the Guardian reports.

"The key issue is how the virus mutates in the southern hemisphere over the next few months during the winter there," said the director of London's World Influenza Centre. "We must prepare as best we can for all these scenarios, and then deal with the ones that unfold. It will probably be a long battle, however." (More H1N1 virus stories.)