The University of Hong Kong is retesting one of its earlier studies on the effectiveness of surgical masks that found they can reduce the spread of viruses by more than 70 per cent. The original study involved HKU, the University of Maryland and Harvard School of Public Health, and was conducted in 2009 in the United States.
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.