Authorities launch nationwide screening program for the virus

Four more people in East China have been confirmed to be infected with the H7N9 bird flu virus, as a nationwide screening program has been launched for the rare but lethal strain.

The health authority in Jiangsu province said four people living in different cities are in critical condition after they developed fever, coughing and other symptoms around March 20. They tested positive for H7N9 on Tuesday afternoon.