"The virus seems new to mankind. The entire world's population could be affected if it gains momentum," said Annika Linde at Swedish Institute for Communicable Disease Control (Smittskyddsinstitutet - SMI) to Sveriges Radio.
The newly discovered flu virus H7N9 in China is a variant of the bird flu, and the first infectious cases became known this year. The virus is known to cause severe respiratory infections.
The virus carries with it a high mortality rate among those infected by the H7N9 virus. At least 43 of the more than 130 infected have died so far, according to WHO statistics.
The mortality rate is far lower than that of the H5N1 virus a decade ago, but higher than the H1N1 that raged from 2009 to 2010.
Annika Linde warned in an article in the esteemed medical journal The Lancet a month ago that the H7N9 bird flu could reinvigorate this autumn and begin to spread worldwide.