HONG KONG: Thousands upon thousands of people in the city have become immune to the human swine flu as they have recovered from unrecorded cases of the disease, a health official said.

The numbers of those developing immunity are growing, said Thomas Tsang Ho-fai, the controller of the Centre for Health Protection. He estimated that several hundred thousand people have been infected as unrecorded cases of the disease since the virus began circulating in Hong Kong early this year and already have developed immunity to A (H1N1) unless the virus mutates.

Tsang said that by Thursday 24, 681 cases of swine flu had been recorded and most patients have recovered.

"We believe that on top of the lab-confirmed cases, there have been an extra tenfold to twentyfold number of cases (in the city so far). This is based on overseas experience and our estimation," he said.

But he warned that more people may contract the disease in the next two weeks, as it remains a peak period for human swine flu.

He said the spread of the virus may slow once a majority of the population comes down with swine flu and then recovers.

Tsang said the number of infections may go down next month or November, but he is not yet certain.

He said human swine flu has become so widespread in the city that about 60 to 70 percent of people with mild flu-like symptoms have the disease.

As a result, the government decided to adjust its ways of monitoring and reporting the spread of the virus in the town, he said.

Beginning next Monday, authorities will no longer report the number of confirmed cases online daily, except for the critical and fatal ones.

The center's website will be updated weekly with the percentage of patients testing positive for human swine flu in the eight designated flu clinics, the number of patients seeking treatment for flu-like illness in those public clinics and the consultation rates for flu-like disease in private clinics, Tsang said.

Under the new policy, he said the government will conduct laboratory tests for the virus in only five patient categories, including pregnant women, children 12 months old or younger, healthcare workers, patients living in nursing homes or other hostels not yet detected with a flu outbreak and those with serious symptoms.

Tsang said the latest figures show that 113 out of 1,000 patients seeking treatment in private clinics had flu-like symptoms - a record number in recent years.

But he said the fatality rate of human swine flu in Hong Kong remains as low as 0.08 percent.

Until Thursday, the city had recorded 19 deaths related to the disease, government figures showed.

Meanwhile, five patients, aged 27 to 41, in a male ward of the Kwai Chung Hospital tested positive for human swine flu in the past week, its spokesperson said.

The hospital suspended admitting new patients to the ward, he said.

China Daily

(HK Edition 09/26/2009 page1)