Scientists scramble to study deadly new bird flu strain

What is worrying health officials is that this new H7N9 strain seems to spread more easily than the notorious H5N1 virus.

“This is definitely one of the most lethal influenza viruses that we’ve seen so far,” said Keiji Fukada, the World Health Organisation’s assistant director general for health security.

So far it doesn’t seem to be as deadly as the H5N1 bird flu virus. That strain killed more than 60 per cent of the 45 people it infected between 2003 and 2013.

But in the two months since it was first identified H7N9 has infected more people than H5N1 managed in a decade.

Closing live poultry markets in the outbreak’s epicentre of Shanghai seems to have reduced the spread. Hong Kong and Taiwan have done the same as a precuation.

But in many cases there is no link to birds. That suggests there may be another unknown source of infection.

The genetic code of the new virus is now being study at labs around the world, including the UK. What researchers want to know is whether it has an ability previous birld flu strains have lacked – to pass from person to person.

“At the moment the H7N9 carries a couple of hallmarks which suggest it’s half way there,” said Professor Wendy Barclay, a flu virologist at Imperial College, London.

“It is a bit worrying but I should stress at the moment there’s no evidence this virus is spreading between humans, and it’s likely there are more barriers to overcome before it does so.”

As it stands, the new bird flu is some way from becoming the next flu pandemic. But it has killed a fifth of all the people it has infected so far, and for that reason alone, it will remain at the top of the global health watch-list.