PARIS: The H7N9 bird flu that hit China this year killed over a third of hospitalized patients, said researchers on Monday who labelled the virus “less serious” but probably more widespread than previously thought.
They warned watchdogs not to take comfort from a lull in new infections, as the virus may reappear in the autumn.
In what they described as the most complete picture of the virus’ severity, researchers in Beijing and Hong Kong found that H7N9 proved fatal in 36 percent of patients admitted to hospital in mainland China.
This was a lower fatality rate than H5N1-type bird flu, which emerged in 2003 and killed about 60 percent of hospitalized patients.
It was higher, though, than the H1N1 “swine flu” outbreak of 2009-10, which had a 21-percent death rate among people requiring hospitalization.
A total 131 human infections have been recorded on the Chinese mainland since the outbreak started in February, the National Health and Family Planning Commission said in its last monthly update.
Of these, 123 were admitted to hospital, and 39 died.
One other case was recorded in Taiwan.
The virus is believed to spread to humans from birds. The fear is that it could mutate into a form transmissible from human to human.
Writing in The Lancet medical journal, the researchers estimated that between 0.16 percent and 2.8 percent of all people infected with H7N9, and who displayed symptoms of flu, were at statistical risk of dying.
“Human infections with avian influenza A H7N9 virus seem to be less serious than has been previously reported,” they wrote.
But many mild, unreported cases may have occurred—between 1,500 and 27,000—said the study, urging “continued vigilance and sustained intensive control efforts.”