Ed Yong, reporting for Nature News:
A team of scientists in China has created hybrid viruses by mixing genes from H5N1 and the H1N1 strain behind the 2009 swine flu pandemic, and showed that some of the hybrids can spread through the air between guinea pigs.
Producing reassortments in the lab doesn’t mean these strains are out in the wild, but they do show it’s possible. Such research helps virologists prepare for potential future outbreaks.