Australia on Saturday defended its escalation of swine flu protection measures as global health chiefs said a vaccine could be ready as early as June and worldwide cases continued to rise.

A passenger filling in a health form due to the alert over swine flu and bird flu at Melbourne Airport on May 3. Australia has defended its escalation of swine flu protection measures as global health chiefs said a vaccine could be ready as early as June and worldwide cases continued to rise.

Prime Minister Kevin Rudd said it was inconvenient but necessary to ramp up Australia's pandemic threat response as the country reported its 14th confirmed infection.

Japan, which has 321 confirmed cases -- most of them domestic infections -- meanwhile relaxed measures imposed to limit the spread of the disease.

The world remains at flu alert level five, signalling an "imminent pandemic," as China, South Korea and Hong Kong also reported new cases on Saturday, a day after Moscow recorded its first infection.

Although it continues to spread around the world, the A(H1N1) virus has a far lower fatality rate than the H5N1 avian flu that has sparked fears of a pandemic in recent years.

Canberra raised its alert level to a containment phase on Friday, after recording the country's first case of human-to-human transmission of the A(H1N1) virus.

The victim is a 10-year-old girl who contracted the disease from a classmate who was taken ill on her return from the United States.

The new phase allows for the closure of schools and other public places and the cancellation of major events, with three schools already shut following the confirmation of cases among students and further closures likely.

Rudd acknowledged the move would inconvenience families, but said it was important to take decisive action.

"Every effort by our public health authorities has been taken to avoid deaths at home," Rudd told reporters.

"We will take whatever actions are necessary to underpin the public health of the nation."

With the exception of a 51-year-old Mexican tourist, all Australia's swine flu cases are younger than 28, and more than half are school-aged children.

Health officials in Japan's Hyogo prefecture, one of the worst-hit parts of the country, on Saturday announced they were easing guidelines for more than 4,800 schools and kindergartens which had been closed to slow the spread of the virus.

The latest official figures from the World Health Organisation (WHO) show 11,168 confirmed cases and 86 deaths have been recorded worldwide since A(H1N1) influenza emerged in Mexico and the United States a month ago.

WHO head Margaret Chan however warned Friday that poorer countries should be prepared for more severe cases.

"Countries especially in the developing world, where populations are most vulnerable, should prepare to see more than the present small number of severe cases," she said.

But in some good news, the WHO said the first vaccine against the A(H1N1) virus could be ready by the end of next month.

"We're hopeful that by the end of June, by the beginning of July, this will be the time that commercial companies will be in a position of being able to make a vaccine," said WHO interim assistant director general Keiji Fukuda.

But Fukuda added the daily count of the rising number of cases around the world was becoming irrelevant.

"The numbers themselves have become a little bit more irrelevant," Fukuda said. "They will increasingly not reflect what's going on.

"Countries such as the United States are moving away from large-scale testing of cases," he said.

Fukuda added though that experts were still mulling whether to give the go-ahead for production as this may reduce or halt the manufacture of vaccines for seasonal flu.

A study released Friday said the various A(H1N1) swine flu strains spreading across the globe react to antibodies in the same way, boosting the chances of a common vaccine for all of them.

The study, published in the US journal Science, says the virus has probably been circulating unnoticed in pigs for some time, and it calls for more careful monitoring of swine populations.

It confirms that the new pathogen originated with the animals, and is a mix of a previously known virus that already contained avian, swine and human genetic segments with two other genes from Eurasian swine viruses never before detected outside Asia.