Encouraging signs: Secretary for Health, Welfare & Food Dr Yeoh Eng-kiong speaks to the press.

The Secretary for Health, Welfare & Food says an encouraging breakthrough has been made with the identification of the virus behind the atypical pneumonia outbreak at Prince of Wales Hospital.

Dr Yeoh Eng-kiong said experts from Chinese University have successfully isolated the virus family causing the infections, adding that the finding has proven that the treatment applied to infected patients has been the right choice.

Dr Yeoh said the virus is believed to be transmitted through droplets, adding that experts are still learning about the bug.

Dr Yeoh said it appeared to be a variant form of a virus that commonly causes respiratory infection in children, however most of the cases reported affected adults.

Reports from Germany and Taiwan appeared to collaborate this, he said, World Health Organisation (WHO) would need to co-ordinate efforts to verify and confirm the findings and more research would be necessary to understand the unusual behaviour of the virus.

As at 1pm today, there were 150 people suspected of contracting severe acute respiratory syndrome in Hong Kong.

Of them, 145 are confirmed to have signs of pneumonia, and the remainder are under observation. Among those infected, five have died and two have recovered and been discharged.

Dr Yeoh stressed that there is no evidence to suggest that the infection has spread to the community. He reiterated that the risk to the general public is low.

Those primarily at risk are those with close contact with infected patients, such as healthcare workers and relatives.

The Hospital Authority's Ko Wing-man said 480,000 surgical masks have been distributed to frontline healthcare workers.