The influenza A(H7N9) virus is one subgroup among the larger group of H7 viruses that normally circulate among birds. A number of human infections of the H7N9 virus have been reported in eastern China, mostly in the Yangtze River Delta region since late March 2013. Some of the patients have died of severe pneumonia brought on by the virus. 

A 69-year-old man from Hebei who contracted the H7N9 virus had been in contact with live poultry before he fell ill. Photo: SCMP Pictures

Four new H7N9 cases reported in north China

Two new cases of H7N9 infection have been reported in Henan province, local health authorities said on Sunday, taking the number of news case in northern China in recent days to four.