Australia is overdue for a massive influenza outbreak which could kill thousands, health experts warn.

Health authorities in Australia have been working with the World Health Organisation (WHO) to develop a new flu vaccine to combat the potentially deadly virus next winter.

But even those who do get the new flu shot from their GP could find themselves unprotected amid an influenza pandemic.

WHO´s global influenza program coordinator Dr Klaus Stohr said pandemics occur every 20 to 30 years, with the last one hitting Australia in 1968.

As a result Australia was now overdue for a pandemic, with the deadly bird flu which has infected millions of chickens in Asia posing one of the greatest threats.

Dr Stohr said so far the H5N1 avian influenza had only been transmitted from chickens to humans, killing about 29 people so far this year.

However, if the bird virus mixed with a human virus and was transmitted between people there could be a pandemic outbreak racing around the world within months.

"We are overdue, certainly (for a pandemic)," Dr Stohr said.

"You have millions of chickens which are affected ... 80 per cent of the farms are backyard farms, a few chickens in the backyard, playing with children.

"So the reason to be concerned is certainly there.

"We have never been as close to pandemic as we are now, that´s the generic assessment of all the experts and also the assessment of the WHO."

Dr Stohr said while there would be no way to stop such a virus spreading globally, it was up to countries to detect it quickly and contain it.

Once it was contained, vaccines could be developed.

Dr Stohr said it was still important for people, especially those aged over 65, to have flu shots, because influenza kills up to one million people a year in developed countries.

"It´s important that we don´t forget that between these pandemics which occur every 20 to 30 years more people are dying from influenza than during these pandemics," he said.