Hong Kong's government on Wednesday ordered all kindergartens and primary schools to close for two weeks amid a growing flu outbreak.
It also asked one of its top scientists to study the deaths of three children over the past week.
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Health secretary York Chow said Yuen Kwok-yung, who helped study Hong Kong's outbreak of severe acute respiratory syndrome outbreak, or SARS, about four years ago, will head a panel of scientists studying the recent deaths.
Chow said it was not clear if the three cases were linked but that he became concerned after the most recent death — that of a 7-year-old boy on Tuesday — because five of his classmates had also been hospitalized.
Chow also announced at a late-night news conference that all kindergartens, primary schools and special education schools will begin the Easter holiday early to prevent the spread of influenza in classrooms.
The closure affects nearly 560,000 students at 1,745 schools, according to enrollment figures from the 2006-2007 academic year.
Classes will resume March 28, Chow said.
Chow said a growing number of people have been suffering from flu and that bringing the Easter break forward would help reduce infections and calm public fears.
"We estimate this peak season of influenza will continue for a few weeks," Chow said.
The cause of the 7-year-old boy's death has not been determined. Officials said some of his classmates were believed to be suffering from flu, and the government closed the school earlier this week.
The five hospitalized classmates were in stable condition, Chow said.
No cause has been determined either in the two other deaths — of girls aged 2 and 3 — officials said.
The deaths came amid a series of flu outbreaks in Hong Kong over the past several days. Health officials have confirmed a total of six outbreaks at schools, a hospital and a nursing home for the elderly since March 6.
The flu outbreaks also have led to crowding at some hospitals, while the number of patients seeking walk-in treatment at emergency rooms has risen 16 percent from the same period last month, Hospital Authority Chief Executive Shane Solomon told reporters.
None of the cases has been linked to bird flu, which was recently detected in birds in Hong Kong.
Bird flu remains difficult for humans to catch, but scientists fear the virus that causes it could mutate into a form that spreads easily among humans and trigger a pandemic that some say could kill millions.
SARS infected 1,755 people in Hong Kong and killed 299.