Researchers in China's Shanghai city have announced preliminary success in developing a vaccine as the country is witnessing a rise in cases of humans getting affected by bird flu, or H7N9 virus.

 

 Officials with Shanghai Public Health Clinical Center said that their genetically-engineered vaccine has passed the preliminary animal tests on mice, Xinhua reported.

 

 The vaccine, however, will have to go through a clinical test to prove its effectiveness in protecting humans before being put into use,  Xu Jianqing, a professor with the center, said. 

 

 Meanwhile, health authorities in Zhejiang province confirmed another human case of H7N9 bird flu, pushing the number of human cases in the province to 74 this year. The 61-year-old man is in a critical condition.

 

 East China's Jiangsu province Saturday reported a human infection in a 53-year-old man, and one person's death due to bird flu, pushing the number of H7N9 human cases in the province to 12 this year.

 

 An H7N9 virus was first reported to have infected humans in March 2013, in China.