By DIKKY SINN

Associated Press Writer

updated 9:20 p.m. ET March 13, 2008

HONG KONG - A top Hong Kong scientist said the flu virus in the territory's current flu outbreak is not deadlier than past viruses, as health authorities kept more than half a million school children at home as a precaution following at least two flu deaths.

Yuen Kwok-yung and a panel of experts studied two flu patients who died amid the outbreak — a 7-year-old boy and a 3-year-old girl — and found that the flu virus had not spread beyond their lungs, which suggests the virus is not exceptionally virulent.

"If it is a more virulent virus, we should be able to find the flu virus in other organs," Yuen told reporters Thursday after a four-hour meeting with his colleagues.

Earlier Thursday, the World Health Organization also said there was no reason for concern.

Spokesman Peter Cordingley called the Hong Kong outbreak "just regular seasonal flu."

"Hong Kong is a flu viruses' playground. It's such a congested city that the lines of transmission of the virus are always there," he said from Manila.

The outbreak has not been linked to bird flu, which has infected birds in Hong Kong. Bird flu remains difficult for humans to catch, though scientists fear the virus that causes it could eventually mutate into a form that spreads easily among humans.

But the government late Wednesday ordered all kindergartens, primary and special education schools closed for two weeks starting Thursday — a move reminiscent of measures taken during Hong Kong's outbreak of SARS, or severe acute respiratory syndrome.

SARS also forced the closure of schools as the disease spread here after surfacing in southern China in November 2002, killing 299 in Hong Kong.

Some parents did not hear about the closure in time and sent their children to school anyway.

Nine students arrived early Thursday at the Cho Yiu Catholic Primary School, greeted by school staff who took their temperature and distributed masks. The students read picture books instead of attending class.

"Some classmates were sick, but they still came to school. I'm worried they have spread the virus and more people will get sick," 11-year-old Wong Pui-shan said.

The closure in effect starts the Easter holiday for schools about a week in advance. The move will affect nearly 560,000 students at 1,745 schools, according to enrollment figures from the 2006-2007 academic year.

The current outbreak hasn't set off widespread panic, as did SARS, which prompted locals to don masks en masse.

Still, 46-year-old banker Edmond Lai said he was washing his hands more frequently and avoiding crowded places _ but wasn't worried about a larger outbreak.

"Locals are more aware about protecting themselves" after SARS, he said.

Hong Kong health officials have reported nine confirmed flu outbreaks and 65 suspected since March 6, mostly at schools, affecting 532 people in the territory of nearly 7 million. At least three children have died amid the outbreak, two of whom were confirmed with the flu.

WHO spokesman Gregory Hartl said the first child who died tested negative for all types of influenza viruses. The second child tested positive for the flu but also suffered from an underlying metabolic disease. The third — a 7-year-old boy who died Tuesday — had both the flu and encephalitis.

On Thursday, Yuen reported similar findings.

He added it's not uncommon for flu to kill, even when there are no pre-existing illnesses.

"It kills Americans. It kills Chinese. It kills Hong Kong Chinese," he said.

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