The Department of Health has detected a strain of human swine flu virus resistant to Tamiflu. The strain is sensitive to Relenza.

The virus was isolated from a 74-year-old man who was admitted to United Christian Hospital October 7 for acute exacerbation of his chronic lung condition. He was discharged October 13.

He took a full course of Tamiflu in late September during another admission, also for acute exacerbation of his chronic lung condition. There is no evidence of further transmission of Tamiflu-resistant swine flu from him.

The case will be reported to the World Health Organisation. So far more than 5,500 swine flu samples have been tested for antiviral sensitivity in Hong Kong.