A major Adelaide hospital has run out of flu vaccines intended for frontline health staff as the number of cases continues to surge across Australia, with sometimes fatal consequences.

Key points: Doctors have predicted 4,000 flu-related deaths this year

Doctors have predicted 4,000 flu-related deaths this year SA has begun rolling out free vaccines, but there is a shortage at Flinders Medical Centre

SA has begun rolling out free vaccines, but there is a shortage at Flinders Medical Centre A 15-year-old girl was the third person to die because of the flu within weeks in SA

There have been more than 33,000 confirmed influenza cases across the nation since the start of 2019 — about 21,000 more than the first four months of last year.

New South Wales and Queensland have recorded more than 16,000 cases between them, with almost 7,500 in South Australia.

Doctors have warned of an expected 4,000 flu-related deaths this year.

On Wednesday, health authorities revealed a 15-year-old girl had become the third person to die in SA from the flu within the last few weeks.

The SA Government launched its free vaccination program earlier this month, several weeks ahead of schedule, to combat the spiralling caseload.

Flinders Medical Centre in Adelaide's south was also in the process of rolling vaccines out to doctors and nurses.

But high demand has led to shortages at the hospital, where staff will have to wait until next week to get their own shots after running out on Tuesday evening.

"We've already given about 2,200 and we're expecting more doses coming in on Monday or Tuesday next week," said Southern Adelaide Local Health Network chief operating officer David Morris.

"A batch of 2,000 would normally last a bit longer."

SA Health Minister Stephen Wade said more than two-thirds of Flinders staff have not been vaccinated.

"The staff vaccination program at this stage is targeted particularly at staff involved in high-risk areas such as the intensive care unit, the older persons unit, the neonatal unit," he said.

"There is no problem with supply of the vaccine. The distribution network operates on a cycle and my understanding is the Flinders Medical Centre will have supplies in the next day or so."

Health staff should be a priority, Opposition says

The state secretary of the Australian Nursing and Midwifery Federation, Elizabeth Dabars, said it was "very, very concerning" that vaccines were currently unavailable to frontline staff.

"It's not compulsory, however it is highly and strongly recommended. Largely, health professionals do take it up," she said.

"It is crucial that they have the maximum coverage possible."

The number of flu cases across Australia is much higher than recent years. ( Immunisation Coalition )

Associate Professor Dabars said it was unclear why the shortage had occurred.

"Is there a strategic decision to stagger or stage inoculations? Because we do know with the flu vaccination the effectiveness peaks after several months," she said.

Opposition spokesman Chris Picton said no vaccines were being distributed to staff at the Royal Adelaide and Queen Elizabeth hospitals.

"To have 2,000 shots for 7,000-8,000 workers at Flinders isn't good enough, to have our biggest hospital — the Royal Adelaide — with no flu vaccine distributed to staff isn't good enough," he said.

"Doctors and nurses — they're the ones who should be getting this vaccine first because if they get sick, they're not there to care for us."

Mr Picton said the Government had been caught unprepared for the rising demand, but Mr Wade said hospital staff had been proactive.

"We'll continue to back our clinicians to make the decisions that are necessary to make sure we have a maximum impact from the vaccination program," he said.