H7N9 bird flu is a 'serious threat' - researchers warn
2 May 2013 Last updated at 03:29 BST
The outbreak of a new type of bird flu in China poses a "serious threat" to human health, but it is still too soon to predict how far it will spread, experts have said.
Of the 126 people known to be infected so far, 24 have died, with many more still severely ill in hospital.
The H7N9 virus has not, however, yet proved able to spread between people - which limits its global threat.
The threat should be "treated calmly, but seriously", researchers advised.
Fergus Walsh reports.