Since it was first discovered in late March of this year, the H7N9 virus has infected 60 people, killing 13. It's not clear whether the virus can spread from person to person. But as the first round of tests on the virus has shown, it has some troublesome characteristics.
Scientists from around the world have been busy studying the virus now that its genome has been sequenced.
Research by He Jianku of South University of Science and Technology of China suggests it can change rapidly; a protein that binds H7N9 to its host's cells may be mutating at a rate eight times faster than in a typical flu virus. He found dramatic mutations of haemagglutinin in one of the four flu strains released for study by the Chinese government; nine of the protein's 560 amino acids had changed. Typically, only one or two amino acids change in such a short period of time.
Nature News is reporting that the new virus has several mutations which make it more adapted to humans than H5N1. According to Jeremy Farrar, director of the Oxford University Clinical Research Unit in Ho Chi Minh City, Vietnam, "This looks very different from H5N1. We never saw this number of presumed avian/animal to human transmissions in such a short space of time."