The virus known as "highly pathogenic avian influenza A H5N1" - and better known for causing "bird flu" - has killed 360 people since 2003, and frightened millions more. The world has spent billions to protect people from the disease, to cull infected poultry flocks and to limit risks from infected wild birds.
At first glance, therefore, scientific efforts to make H5N1 more easily transmissible seem imprudent, to say the least. Terrorists or a rogue government could use such a strain as a bioweapon; and even a lab accident could let loose a new, self-inflicted horror on humankind.
And yet 40 researchers in virology have announced, in the journals Science and Nature, that they are ready to suspend the moratorium they imposed on themselves a year ago, after colleagues voiced fears.
This is the right approach. Dangerous new flu viruses keep emerging naturally: we need to learn all we can about the process, to help stop a new genuine, deadly global epidemic like the one that killed 20 to 40 million people in 1918-19. Governments and multinational agencies will develop security protocols before this research proceeds.
As with so much in modern life, the challenge here is to manage a risk while pursuing a rewarding result.