The World Health Organization's move to declare the first global flu pandemic in four decades will do little to change Canada's response to the H1N1 virus, Canada's health minister says.

"I want to reassure Canada . . . we were prepared for this decision and this decision does not change our approach in Canada," Health Minister Leona Aglukkaq said at a Thursday afternoon news conference.

"It is primarily a technical decision (by the WHO)," Aglukkaq said. "Thankfully, the vast majority of illnesses remain mild."

Canada's chief public health officer said the WHO move was "based on the spread of the virus, not the severity."

"We will continue to tailor our domestic responses and public health measure to our own situation and to the evolving needs of Canadians," Dr. David Butler-Jones said at the news conference. "Within our borders . . . the virus continues to behave like the seasonal flu."

WHO warned Thursday morning that H1N1 is still spreading and is causing a moderate pandemic around the globe.

"The world is now at the start of the 2009 influenza pandemic," WHO Director General Dr. Margaret Chan said as she moved the flu pandemic alert level to Phase 6 -- its highest level.

"We are satisfied that this virus is spreading to a number of countries and it is not stoppable."

H1N1 has been reported in 74 countries, has caused 141 confirmed deaths and at least 27,737 cases of illnesses.

While the total number of deaths is small, H1N1 is still more serious than regular flu. About half the people who have died were previously young and healthy -- people who are not usually susceptible to flu.

"Each and every one of these deaths is tragic and we have to brace ourselves to see more," Chan warned. "However, we do not expect to see a sudden and dramatic front in the number of severe or fatal infections."

The last pandemic -- the Hong Kong flu of 1968 -- also caused moderate illness but killed about 1 million people. Ordinary flu kills about 250,000 to 500,000 people each year.

The pandemic announcement means countries will now immediately activate their pandemic plans. The announcement will also trigger drug makers to speed up production of an H1N1 flu vaccine.

Canada has signed a contract with pharmaceutical giant GlaxoSmithKline to produce a vaccine for H1N1 when one is developed.

The WHO is urging nations not to close borders or restrict travel and trade, though it remains to be seen how closely that advice is followed.

Australia the tipping point?

The development that likely triggered the pandemic announcement was the sudden "community spread" of H1N1 in Victoria, Australia, which signalled it was entrenched in another region besides North America.

"Swine flu" cases in Australia soared to more than 1,000 on Monday and reached 1,260 by late Wednesday. The country now has the fifth-highest number of cases worldwide, after the United States, Mexico, Canada and Chile.

"We have tested 5,500 people in the last two weeks, that is more people than we test in our whole influenza season," Victorian state Premier John Brumby said Thursday as he defended his government's handling of the flu virus.

"Elsewhere around the world, in the United States and Canada, they are only testing the most serious cases."

The WHO has also expressed concern about the "disproportionate number" of serious cases on native reserves here in Canada.

Hundreds of aboriginals in the tiny community of St. Theresa Point, 500 kilometers northeast of Winnipeg, have reported symptoms. More than a dozen have been treated in hospital and several are on ventilators.

The WHO believes the disease can take a harsher toll on people facing poverty, substandard housing and underlying health problems.

"If we see spread of this virus into populations which are especially vulnerable, it means that we may see more severe disease than we would see in populations which are relatively well off. I think the current reports coming from Canada ... is a good example of this," Dr. Keiji Fukuda, the WHO's acting assistant director general for health security and environment said earlier this week.

Hoping to avoid panic

With many criticizing the WHO's pandemic scale, the agency had been under pressure not to raise the alert to the highest level so as to not cause panic. There have been worries that the declaration would cause hospitals to become overwhelmed by people with only mild illness seeking care, while other patients requiring treatment risked being neglected.

That has already happened in Argentina, even without the pandemic declaration. There, thousands of people have flooded hospitals this week, bringing emergency health services in the capital of Buenos Aires to the brink of collapse.

Most indications suggest the virus is on the decline, after peaking last month. But health officials are preparing for a resurgence in the fall.

Some experts say the WHO's made an unnecessary move to declare H1N1 a pandemic and it will only cause a panic.

"Moving is irresponsible. It's based on a technicality," Ontario public-health physician Richard Schabas told CTV News Channel Thursday.

"Going to level six is not based on good science . . . We're seeing far too mild (conditions) and infections are far too low."

He says that if H1N1 fizzles it will undermine the public's confidence in the WHO's flu system.

Several Asian governments has already prepared for even tighter flu controls, after reportedly receiving advance notice of the WHO announcement.

The Chinese territory of Hong Kong ordered all kindergartens and primary schools closed for two weeks, after 12 students were infected. And a school in Bangkok will be shut for a week after four students were infected.

China has been quarantining people exposed to the virus, including a group of university students from Quebec who were released after almost a week quarantined in a hotel.

The WHO warned that countries where the H1N1 virus appears to have peaked need to remain vigilant and prepare for a second wave of infections because the flu is unpredictable.

"When you are over with the first wave, start preparing for the future," Chan said.

"This early patchy picture can change very quickly. The virus raised the rules, and this one, like all influenza viruses, can change the rules without rhyme or reason at anytime."

With reports from The Associated Press