There is no evidence of human-to-human spread of the resurgent H7N9 bird flu virus after a doctor in Shanghai was confirmed to have died from the infection, Chinese health authorities said Tuesday.

Shanghai's health commission confirmed Monday that two men died Saturday from the H7N9 strain of bird flu, including Zhang Xiaodong, a 31-year-old emergency room surgeon at Shanghai Pudong New Area People's Hospital.

Zhang is the first doctor who is reported to have contracted the virus, causing concern that the virus could be transmitted from human to human. The second victim was a 77-year-old farmer, whose name was not given.

According to the Chinese Center for Disease Control and Prevention (China CDC), more than 200 human cases of H7N9 infection have been reported nationwide since March 2013, with an intensive outbreak from December 2013 to January 2014, most found in East China.

Feng Zijian, vice director of the China CDC, told the Global Times on Tuesday that there is no evidence that H7N9 is contagious enough to pass from human to human.

"The danger posed by the virus and its capacity to be transmitted has not changed since the first H7N9 case was reported last year. The current H7N7 strain is no more virulent when it comes to infections or causing death," Feng said.

H7N9 poses more threat to a victim than those with a dose of normal seasonal flu, as it mimics the symptoms of regular flu for the first three to five days, but does not respond to normal flu treatment, experts said.

The patient could then suddenly deteriorate between the fifth and ninth day of infection, and it was often too late when doctors realized it was an H7N9 infection and tried to use the right medication.

Zhejiang, which is the worst-hit   province in China, reported three new cases on Tuesday, bringing its total infected this year to 29 people.

According to Shanghai Morning Post, seven of the 60 infected people nationwide had died as of Monday.

Lu Hongzhou, vice director of the Shanghai Public Health Clinical Center, also said there is no evidence that Zhang was infected by a person, as none of his patients showed traces of the virus.

Zhang's family and the doctors who treated him are being closely monitored, but so far, none has developed influenza-like symptoms, Lu told the Global Times.

"Zhang probably inhaled air that contained the virus although he didn't have any direct contact with live poultry. He lived in Chuansha, Pudong New Area, an area that's a mix of urban and suburban, where residents raise a lot of poultry," Lu said.

On January 4, Zhang visited his parents whose neighbors keep doves. There is also a live poultry market near the hospital where he worked, the Shanghai Municipal Commission of Health and Family Planning said Monday in a statement.

Zhang developed symptoms on January 11 and was treated in hospital on January 15, but did not feel better. His condition deteriorated on Friday and he was sent to intensive care, but died Saturday morning.

About 70 percent of the H7N9 victims had close contact with live poultry or had been to markets with live poultry, Feng told the Global Times.