Detection of human swine influenza virus resistant to Tamiflu

3 Jul 2009

A spokesman for the Department of Health (DH) said the department's Public Health Laboratory Services Branch (PHLSB) today (July 3) detected a strain of human swine influenza (HSI) virus which was resistant to oseltamivir (Tamiflu).

The virus was identified during PHLSB's routine sensitivity test of HSI virus to oseltamivir and zanamivir, the spokesman said.

"This is the first time Tamiflu resistance in HSI virus found in Hong Kong," he said, adding that similar cases were also reported in Denmark and Japan.

"Tests showed that this strain is sensitive to zanamivir (Relenza)," he said.

The virus was isolated from the specimen taken from a 16-year-old girl coming from San Francisco. She was intercepted by Port Health Office at the Hong Kong International Airport on June 11 upon arrival.

The girl was then admitted to Queen Mary Hospital for isolation. She was tested positive to HSI but opted not to take tamiflu. She had mild symptoms and was eventually discharged upon recovery on June 18.

The spokesman noted that PHLSB conducted routine sensitivity tests on specimens taken from confirmed HSI patients.

"This is the only Tamiflu-resistant strain so far among some 200 HSI samples tested in Hong Kong. Further tests are underway," he said.

Hong Kong has maintained an antiviral stockpile of both Tamiflu and Relenza.

The case will be reported to the World Health Organization (WHO), the spokesman said.

He reiterated that Hong Kong had an intensive influenza surveillance system on antiviral resistant influenza viruses.

"We will closely liaise with WHO and overseas health authorities and monitor the global development of antiviral resistant HSI virus," he said.