New H7N9 cases raise fear of its spread

With three patients, including one in Hangzhou and two in Hongkong testing positive for the H7N9 virus last week, concerns have increased that the strain of the deadly bird flu could further spread in winter.

A 30 year old man has been diagnosed with bird flu in Hangzhou. He is the son-in-law of another H7N9 patient who was diagnosed one week earlier. But whether he caught the virus through human-to-human transmission is still not clear.

"The evidence is not clear. We can't rule out the possibility that the father transmitted the virus to his son in law, because they were not living together before the father caught bird flu. But after the father was sick, the son was looking after him." Li Lanjuan, director of Infectious Diseases Lab, said.

With winter underway, the flu has intensified. New bird flu cases have raised the concern that the deadly infection may be on the up.

Reporter: "Last week two Hongkong residents were confirmed as H7N9 patients. Both of them have visited Shenzhen. Now authorities are testing the samples of Shenzhen poultry market, but haven't detected the virus yet. However, these cases show the strain of bird flu is still a threat to public."

A vaccine against H7N9 was announced in October. Mass production is expected to start after clinical trials. Though the timeline for vaccine production has not yet been released, it could be an effective way to prevent the spread of the virus in the future.