The medicines regulator has given provisional approval to a Pfizer COVID-19 vaccine booster for children aged five to 11.

However the Therapeutic Goods Administration (TGA) said on Wednesday the government's decision on the use of this vaccine as a booster in this age group would be informed by advice from the Australian Technical Advisory Group on Immunisation (ATAGI).

At its most recent meeting, ATAGI considered evidence in relation to the Pfizer booster for five to 11 year olds, including disease burden, durability of protection against infection and severe disease, safety and international recommendations.

It said if the TGA registered the booster dose, it would make recommendations.

Children aged five to 11 years are currently recommended to have a primary course - two doses for most people - of a COVID-19 vaccine.

Meanwhile, with commuters almost Australia-wide no longer required to wear masks on public transport, doctors warn ditching the mandate will have consequences.

On Wednesday, NSW and Queensland join South Australia, WA, Tasmania and the NT in not requiring passengers on public transport to mask up.

Victoria will follow suit at midnight on Thursday while masks remain mandatory on public transport for people aged 12 and older in the ACT.

NSW Premier Dominic Perrottet said removing the mask mandate was a common-sense approach, bringing the rules into line for people travelling on buses, trains, ride-share vehicles, taxis and planes.

NSW Health still recommends people wear masks where they cannot physically distance and in settings where there are vulnerable people.

Queensland Health Minister Yvette D'Ath is asking commuters to wear masks when appropriate.

"There are still directions. If you are someone who has been isolating, after your five days you are requested to wear masks," she said.

Australian Medical Association president Steve Robson said governments continued to make serious decisions with no consultation and no discussion.

"This is a major decision which will have consequences, and it should have been done with national consensus and clear health guidance," he said.

"Masks kept us safe from infection when we didn't have a vaccine, and they continue to be an effective, low-cost, low-hassle and proven way to protect ourselves and others."

Prof Robson said COVID-19 was still very serious, particularly for vulnerable populations, and was deadly for many people.

"Restrictions are being loosened, including time in isolation, and we still don't have any sign this was based on medical evidence," he said.

Prof Robson said the decision came at a time when worrying data was still being released, including in relation to aged care.

"Many of our most vulnerable people in the community are the ones that use public transport the most,'' he said.

"Masks are the last of the sensible protections, and we urge people not to abandon using them."

Federal Assistant Health Minister Ged Kearney has also announced investment in a new study into COVID vaccinations and infection in children and people with chronic diseases.

Ms Kearney says there is a research gap about the impact of the virus on vulnerable groups.

"This research will ultimately help to improve the care that children and adults receive, who are at a higher risk of becoming seriously ill from COVID," she said.

The study will be undertaken by Monash University.