Five people with swine flu have been admitted to intensive care units in Melbourne as the number of people infected nationally rose to 1260.
At least one of the five was admitted to hospital with underlying health conditions, a spokesman for the Department of Human Services said.
He could not say how old the patients were.
"What the underlying causes of their illness is, I don't know. They are certainly not well and need to be managed in ICU," he said.
"In one case, the person is in hospital because of trauma, so the H1N1 is unrelated."
Swine flu facts: the virus, the symptoms, the treatmentResidents at three Victorian nursing homes are also being tested for the potentially deadly virus.
Victoria's acting chief health officer Dr Rosemary Lester said health authorities were working with three nursing homes where a number of residents had reported flu-like symptoms.
"As is the usual practice in such instances, symptomatic residents have been isolated and movement of residents and staff has been restricted,'' Dr Lester said.
"Action being taken also includes the restrictions of visitors to the facility until the cases have resolved. Nose and throat swabs have been taken from the symptomatic cases for testing at VIDRL (Victorian Infectious Diseases Reference Laboratory)."
Dr Lester said health authorities expected some people would become seriously ill after contracting swine flu.
Of the 1260 people across Australia who have tested positive for the virus, more than 1000 are in Victoria.
"I think as we've seen the numbers of cases grow, we would have expected, unfortunately that some people will become seriously ill,'' Dr Lester said.
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