On 2 February, scientists and public-health officials squared up to each other in a panel discussion at the New York Academy of Sciences. Debate raged around the fate of two papers that describe mutant forms of avian influenza virus H5N1. These mutated viruses have been shown to be transmissible between ferrets, which has raised concerns that they would be transmissible between other mammals, including humans, with potentially devastating consequences. Several panellists sat down with Nature to discuss their positions.

A full video of the two-hour debate is available from the New York Academy of Sciences. See also our online news special on the H5N1 controversy.