Experts are concerned about the spread of a new strain of bird flu that has already killed one woman in China.
The 73-year-old from Nanchang City caught the H10N8 virus after visiting a live poultry market, although it is not known for sure if this was the source of infection.
A second person has since become infected in China's Jiangxi province.
Scientists told The Lancet the potential for it to become a pandemic "should not be underestimated".
Continue reading the main story
Start Quote
Previously we did not think that H7N9 infections might be so lethal. Now we also must consider H10N8 infections as well
Dr John McCauley
Director of the WHO Collaborating Centre for Influenza
This particular strain of influenza A virus has not been seen before.
In recent months, China has already been coping with an outbreak of a similar influenza virus called H7N9, which has killed around a quarter of those infected.
Pandemic risk
Scientists who have studied the new H10N8 virus say it has evolved some genetic characteristics that may allow it to replicate efficiently in humans.
The concern is that it could ultimately be able to spread from person to person, although experts stress that there is no evidence of this yet.
Dr Mingbin Liu from Nanchang City Centre for Disease Control and Prevention said: "A second case of H10N8 was identified in Jiangxi province, China, on 26 January 2014. This is of great concern because it reveals that the H10N8 virus has continued to circulate and may cause more human infections in future."
