When the 2009 H1N1 flu virus emerged last April, it triggered the first new pandemic in more than 40 years, producing endless headlines and panic. But, now, some 10 months into the pandemic, the public's fear has subsided. H1N1 turned out to be relatively weak, and action by global and national health officials has helped blunt the damage caused by the virus; by mid-February, more than 16,000 people worldwide had died from the new flu, according to the World Health Organization (WHO), but that figure is in line with mortality in a normal flu year.

On Tuesday the WHO will convene a special panel that could begin the process of declaring an official end to the pandemic. "We hope that the worst is behind us and the overall trend will be going down," said Dr. Keiji Fukuda, the WHO's special adviser to the director-general for pandemic influenza, in a Feb. 18 press conference.

But the close of the H1N1 pandemic does not eliminate the long-term threat from influenza. Another pandemic could arise at any time, and a new paper published in the Feb. 22 Proceedings of the National Academy of Sciences (PNAS) demonstrates that it could even come from an existing flu virus that many of us have forgotten about: the H5N1 bird flu, which has infected 478 people in 15 countries since 2003, with 286 deaths - a fatality rate higher than 50%.