Some say it's a nightmare scenario out of the old movie Outbreak with Dustin Hoffman or the newer Contagion by Steven Soderberg: a pandemic caused by the accidental release of a man-made strain of lethal H5N1 bird flu virus.
Could such a disaster happen in real life?
The question is serious and timely. Two teams of researchers who have created such a deadly viral strain agreed last month to halt their work for 60 days, because of concerns that bioterrorists could turn the engineered virus into a weapon.
The two research teams, in the Netherlands and the United States, announced in September that they had independently created an H5N1 strain that was transmissible between people and lethal in more than 50 per cent of cases.
Their virus has been transmitted between ferrets that merely breathed the same air, which is a clear indicator to virologists that the strain could travel easily between people.
Such a flu virus may spread as rapidly as ordinary seasonal flu, but it is several degrees of magnitude more deadly.