Mainland health authorities confirmed two new cases of swine flu yesterday, bringing to 11 the number of people infected with the H1N1 virus. The 10th case was a student at a university in New York who flew back to his hometown Wenzhou , Zhejiang , via Shanghai on Friday, according to the Ministry of Health. The 19-year-old man had a fever and went to a Wenzhou hospital the next day, when he developed a cough, a sore throat and had a 38 degrees Celsius temperature. He was reported as a suspected case on Sunday and was confirmed yesterday. Health authorities have put two family members and two medical workers under observation. It is also trying to track down those who were on the same China Eastern Airlines plane as the man - flight MU588 from New York to Shanghai and flight MU5585 to Wenzhou. The other confirmed case was a Chinese man working for an Australian company who flew from Melbourne to Shanghai on Air China flight CA178 on Saturday and was quarantined at Shanghai's Pudong airport checkpoint because he had a fever of 38.8 degrees. On Sunday his temperature was 38.7 degrees, and he had a cough. Thirty-one people who had close contact with him were under surveillance. Over the weekend, authorities confirmed two people had come down with the virus: a 46-year-old Chinese man in a Beijing hospital back from Canada and a 21-month-old Chinese girl in Fujian returning from the US. Four of the 11 patients have been discharged from hospital. The others were in a stable condition last night.