Hong Kong's H1N1 tally has grown to 23 with three new imported cases confirmed today, the Department of Health says.

The first case involves a 21-year-old man who stayed in the US May 15 to 27 and returned to Hong Kong May 28 from New York on flight CO099. He wore a face mask during the flight and sat in row 23. He took the Airport Express to Tsing Yi where he took a taxi to his home in Cheung Hang Estate, Kwai Tsing.

He developed a fever and sore throat after arriving home. He consulted a private doctor yesterday morning and was sent to Princess Margaret Hospital by ambulance. His family members are asymptomatic.

The second case involves an eight-year-old boy living in the US. He arrived in Hong Kong with three family members today from San Francisco on flight SQ1. He was sitting in row 39. He developed a fever, cough and runny nose during the flight. He was intercepted by Port Health Officers and was transferred to Princess Margaret Hospital by ambulance.

The third case involves a 19-year-old woman studying in the US. She returned to Hong Kong from New York in the evening of May 28. She and her mother took an airport bus to Wan Tsui Estate in Eastern District. She went to China Travel Agency in Shau Kei Wan and to the Immigration Department in Wan Chai yesterday. She came down with a fever, cough and sore throat in the afternoon and her mother took her to Pamela Youde Nethersole Eastern Hospital by minibus. As she developed symptoms more than 12 hours after her arrival, the Centre for Health Protection will not trace the flight passengers.