H7N9 avian influenza is emerging as the virus most likely to cause the next flu pandemic. The good news: It' not so adept at spreading from human to human. The bad news: It' potent, it' better adapted to our respiratory tracts than the more widely known H5N1 virus and it' increasingly prevalent in people. Known to be circulating only within China, H7N9 has been mutating in sinister ways this past year, putting scientists on alert as the cold weather approaches and the strain enters its sixth winter.
1. How bad is this flu?
On paper, horrific. Of 1,562 laboratory-confirmed cases, 569, or 36 percent, have been fatal. That compares with HN51' 453 deaths globally since 2003. But some researchers think those reported H7N9 cases represent just a tiny - albeit much sicker - subset of the infected population. A 2014 study in Guangzhou estimated the number of cases there to be 64,000, with 3.6 deaths for every 10,000 people infected. That would make H7N9 far less severe than the reported cases suggest, though far more widespread.