Swine flu is this year's dominant influenza

SWINE flu has become Australia's dominant influenza strain, with experts predicting that as many as four out of five flu suffers will have the H1N1 virus.

Testing results for swine flu in Victoria have revealed that the H1N1 virus has dramatically overtaken existing strains of seasonal influenza to become the dominant species of winter flu.

The World Health Organisation's Ian Barr, who is deputy director of the Collaborating Centre for Reference and Research on Influenza, said that in the latest sentinel test results, carried out by GPs across Victoria, as many as 99 per cent of people with influenza had tested positive to the swine flu virus.

Dr Barr said these results were high and while there is a variation in results from state to state, "the approximate figure would be closer to 50 to 80 per cent of people overall".

Dr Barr said more people appeared to be contracting swine flu than other influenza strands, but he said this might not be a trend in winters to come.

"It may peter out towards winter's end, or there is a possibility that, like previous influenzas, it may wipe out other flu species," he said.

While estimates from Victoria's Department of Human Services are more conservative, a DHS spokesman confirmed: "We would expect swine flu will become our major influenza this season."

A 45-year-old man has become the first person in NSW -- and the 10th in the country -- to die with the swine flu virus. The man, who collapsed at his home on Monday, had a pre-existing medical condition.

Meanwhile, the death of a three-year-old boy in Victoria, who had tested positive to the virus, is being investigated by the state coroner.

The child died at his home at Doveton, in Melbourne's southeastern suburbs, on June 26.

While experts say most cases of swine flu in children will be mild, a leading disease expert said twice as many children will die from swine flu than from regular influenza throughout the winter flu season.

Robert Booy, from The Children's Hospital at Westmead in Sydney, said in the next year, 10 to 12 children could die from the H1N1 virus, whereas in an average winter, three to six deaths would be expected. But he added that most of these deaths would occur when there was an underlying medical condition.