H7N9 is a new subtype avian flu virus that found for the first time in 2013 at the end of march in Shanghai and anhui province,in China.H7N9 bird flu is the world's first discovery of new subtype influenza virus, It has not been included in the statutory report of infectious disease monitoring system in our country, and there is no any vaccine to launch in early April 2013.

All human influenza virus can causes bird flu, but not all of the bird flu virus can cause a human influenza.The bird flu virus, H3, H5, H7 and H9 could infect people,and the H5 is highly pathogenic,human and dogs could infect H3. According to feature of the influenza virus, the influenza virus can be divided into 135 kinds of subtypes, expressed as HxNx, H7N9 subtype of avian influenza virus is one of them. Before,avian influenza be only found in poultry, we haven't found human infections with these viruses. There is no basis to analyze the biological characteristics,pathogenicity and spread of the virus.

Now there have been people infected with the virus, so we should attach great importance to the livestock disease prevention and control. We need to focus on animal health.