The report, compiled after the WHO's week-long field assessment of the influenza, was publicised by China's National Health and Family Planning Commission yesterday.
The H7N9 virus, compared with other bird flu virus, has infected more in a shorter time, and some H7N9 virus have shown genetic alterations which means they have adapted to be more contagious than other avian influenza virus, report said.
WHO has offered several suggestions to the Chinese government, including staying alert despite the virus' seasonal weakening during the summer, as the virus poses grave hazards and a lot of its basic information are still not known, state run Xinhua news agency said.
The WHO last month sent a joint mission of experts to China to survey areas affected by H7N9 in Shanghai and Beijing for a week-long assessment of the influenza.
From late March when the first H7N9 case was reported to May 13, the China had reported a total of 130 confirmed H7N9 cases.
Out of these, 35 ended in death while 57 patients have recovered and been discharged from the hospital, according to official statistics.