Another human H7N9 case has been found in east China's Jiangsu Province, the provincial health department confirmed on Friday.

The patient, a 75-year-old woman from the provincial capital of Nanjing, is in a critical condition. The case brings the number of infections in the province to eight this year.

H7N9 has killed 19 in China this year, and the total number of human infections reached 96 on Monday, according to the Chinese Center for Disease Control and Prevention.

With bird flu cases increasing on a daily basis, public concern over people-to-people transmission during Spring Festival is growing.

Li Lanjuan, researcher at the Chinese Academy of Engineering and a specialist in H7N9 prevention, said so far there have not been any cases in which one person transmits the flu to another, and the latter transmits the virus to a third person.

Her team has identified H7N9 virus mutations this year, but the mutations are not large-scale.

"Inter-human transmission is very unlikely," said Li, who added that the virus has not evolved to be extensively drug resistant.

The National Health and Family Planning Commission said on Wednesday live poultry markets should close if any case of H7N9 avian flu is detected.

The southern metropolis of Shenzhen has closed all live poultry markets until Feb. 13 for a thorough cleaning. The city near Hong Kong has reported 14 human H7N9 cases since Dec. 18.

Live poultry trading has been halted in Hangzhou, Ningbo and Jinhua cities in Zhejiang, which reported the largest number of human H7N9 cases.

China has stepped up research for an H7N9 vaccine in the face of the increasing threat from the virus.

Beijing's Sinovac Biotech Ltd., which developed the A/H1N1 and H5N1 vaccines, said in a press release on Wednesday that it has completed preclinical studies of an H7N9 vaccine and prepared several types for clinical testing.

The company has submitted an application to the China Food and Drug Administration to start clinical trials.

Hualan Biological Engineering Inc. said in early January that the H7N9 vaccine developed by its subsidiary, Hualan Biological Bacterin Co., Ltd., had passed an initial examination by the food and drug watchdog in central China's Henan Province.

The vaccine is being handled by the China Food and Drug Administration, but it is still hard to say when and if it will be approved for production, according to the Henan Provincial Food and Drug Administration.