Epidemiologist Adrian Esterman wants the Australian Technical Advisory Group on Immunisation to follow the United Kingdom’s lead and recommend boosters three months after a second dose.

He fears leaving the gap at five months will result in “thousands of people infected for no reason”.

The University of South Australia professor anticipates booster shots becoming an annual event, if not more frequent than that.

“But at the moment, it’s still difficult to get a booster shot because of ATAGI’s ruling,” he told AAP.

“What we’ll see is that states and territories will be reintroducing more public health measures because they have to because our hospital systems will be too stretched.”

NSW on Sunday recorded 2566 new infections. There are 227 people in hospital, 28 of them in intensive care.

Professor Esterman thinks that state is in deep trouble as Premier Dominic Perrottet refuses calls to mandate masks indoors and bring back QR code check-ins for all venues.

“The epidemic curve (in NSW) is almost vertical. Cases are doubling every three days,” he said.

“I don’t think lockdowns are necessary, but states and territories should retain their public health measures.”

Victoria reported 1240 new cases and four more deaths. It has 392 COVID-19 patients in hospital, 81 of them in intensive care.

South Australia reported 80 new COVID-19 cases, Queensland 42 and the ACT 18.

There were nine in the Northern Territory as authorities there anticipated extending a lockdown in the town of Tennant Creek.

Tasmania reported three new infections as it prepared to mandate masks indoors.

Australia’s full vaccination rate for people aged 16 and older is sitting at 90.42 per cent. The first dose rate is nearing 94 per cent.

The number of boosters delivered into arms exceeds 1.3 million, with more than 640,000 doled out in the last week.

-AAP