Fifth COVID-19 vaccine - a third booster - not expected until next year, as ATAGI weighs up options

Associate Professor Nathan Bartlett said ATAGI would be weighing up when to introduce the next dose.

"I think they'll hold off on rolling out a third booster for now in this period of relatively low infections," Dr Bartlett said.

"There's still a good level of immunity in the community and cases are still relatively low. But there are still COVID infections around and people in hospital."

Dr Bartlett, a virologist, believes there will be another round of vaccinations rolled out prior to winter next year.

"We could be faced with a new variant we're not protected against and might need to accelerate that. We need to play that by ear."

The latest ATAGI [Australian Technical Advisory Group on Immunisation] advice for COVID vaccines remains at four doses, including two boosters. The new Moderna vaccine, which includes protection against Omicron, can be taken as part of the four doses.

Only severely immunocompromised people aged 16 and over are recommended for a fifth dose.

Dr Bartlett said vaccine fatigue would be a consideration in ATAGI's thinking around the next move. Plus, many people still haven't had their first and second boosters, so there is concern about confusing the public.

The latest figures show 56 per cent of the eligible population in Australia have had three or more shots. About 42 per cent of the eligible population, which is those 30 and over, have had a fourth dose.

ATAGI has advised people 50 and older and those with health conditions to get the fourth dose. People aged 30 to 49 can receive a fourth dose if they choose.

Professor Peter Wark, a senior staff specialist in respiratory medicine at John Hunter Hospital in NSW's Hunter region, said "the big question is what is going to happen next".

Professor Wark said the efficacy of the vaccines to prevent infection had dropped considerably with Omicron.

"The vaccines were always introduced to prevent serious complications of infection, as opposed to infection. We still see very good protection against hospitalisation and death

"It is hard to know what will be offered next, but it makes most sense that people will be offered a booster moving into next year."

While the vaccines begin to wane after three months, NSW Health say boosters help strengthen the immune system and improve long-term protection against the virus.

Professor Joshua Davis, a John Hunter Hospital infectious diseases specialist, said "there's still detectable antibodies for six months or more after vaccination".

Professor Davis said he got his fourth shot a few weeks ago before going overseas.

He said a new Omicron variant was "starting to raise its head in Singapore and other places and we're starting to see a bit of it here".

"There's a pretty decent chance we'll have another wave in the next couple of months before Christmas, maybe not as big as we had when Omicron first came."

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He said the vaccination program should continue, as without more boosters more severe disease could arise.

Dr Bartlett said he strongly believed in the importance of the vaccines.

"They're absolutely essential to maintaining population immunity," he said.

If you lose that vaccination protection, you have a population with a lot lower immunity and that's when those infections will cause more severe disease.

"You want background immunity without the disease and that's what vaccines are. Sure infections will give you immunity, but at the price of disease and that's obviously going to kill some people, so you don't want that."

COVID data is expected in the next few months for the northern hemisphere winter.

"In the UK they had another wave, but it already looks like it's tapering off. In the US, it looks like they are having a winter surge, but it doesn't look as big as we've seen in previous waves at this stage. Early signs are good, but that's probably because there's so much pre-existing immunity."