Swine Flu Jumps Back to Pigs and Keeps Evolving

A new strain of swine flu shows that the pandemic version has jumped from humans back to pigs, where it’s evolving in new and unpredictable ways.

The new strain, identified in a Hong Kong slaughterhouse, isn’t especially virulent. But the findings emphasize the need for continued vigilance. Swine flu isn’t going away.

“Hoping for the best while preparing for the worst seems a sensible strategy,” said University of Hong Kong virologist Malik Peiris. The strain is described June 18 in Science.

Peiris and study co-author Yi Guan are best known for identifying the SARS virus and helping to contain its 2003 outbreak. They were also among the researchers who identified swine flu’s origins after its outbreak last year.