Dr. Jeremy Farrar, chief scientist at the World Health Organization (WHO), said that the avian influenza virus, which is also known as H5N1, has had an “extremely high” mortality rate among the several hundred people known to have been infected with it to date.

However, no human-to-human H5N1 transmission has yet been recorded.

“H5N1 is (an) influenza infection, predominantly started in poultry and ducks and has spread effectively over the course of the last one or two years to become a global zoonotic – animal – pandemic,” he said. 

“The great concern, of course, is that in doing so and infecting ducks and chickens – but now increasingly mammals – that that virus now evolves and develops the ability to infect humans. And then critically, the ability to go from human-to-human transmission.”