Bird flu 'kills more than a third'
More than a third of patients infected with a new strain of bird flu died after being admitted to hospital, researchers have said.
Since the new H7N9 bird flu broke out in China in late March, the strain has affected more than 130 people and killed 37.
The World Health Organisation has described H7N9 as "one of the most lethal influenza viruses" it has seen and said it appeared to spread faster than the last bird flu strain, H5N1, which threatened to unleash a pandemic.
After making some adjustments for missing data, Chinese scientists estimated the overall death rate to be 36%. The outbreak was stopped after China closed many of its live animal markets - scientists had assumed the virus was infecting people through exposure to live birds.
That makes the new strain less deadly than H5N1, which kills about 70% of the people it infects, but it is more lethal than the swine flu that caused a 2009 global epidemic, which had a death rate of less than 1%.
The results were released in two papers on the H7N9 strain, published online in the journal Lancet.
"The good news is that numbers of (H7N9) cases have stalled," Cecile Viboud and Lone Simonsen of the US National Institutes of Health wrote in a commentary accompanying the article.
However, they warned that the threat of the virus "persists" and predicted that the strain might return in the winter when flu viruses are typically most active.
That assessment echoes the WHO, which earlier this month also warned of the virus adapting.