More new infections with the strain were recorded in NSW and the ACT on Sunday.

"When a new variant comes we have to check everything," the head of the Therapeutic Goods Administration John Skerritt told reporters on Sunday.

"But we're quietly optimistic, but I think it is important to be cautious, and emphasise we'll know a lot more in the next seven to 14 to 21 days."

Treasurer Josh Frydenberg also urged people not to panic.

"I think everyone should keep their heads and we should be calmly and safely reopening as we have been," he told ABC's Insiders program.

NSW recorded two more Omicron infections on Sunday, bringing the state's total to 15, and further cases are expected to be confirmed.

In total, NSW recorded another 286 new cases of coronavirus, while a man in his 60s died from the disease.

The ACT also confirmed a second case of the Omicron variant, a close contact of the previous reported individual.

ACT Health reported six new COVID-19 cases on Sunday.

Victoria recorded another 980 virus cases on Sunday and a further seven virus -related deaths.

Professor Skerritt and Health Minister Greg Hunt announced on Sunday that children aged five to 11 years will be able to get a vaccine next year.

Vaccine experts at the Australian Technical Advisory Group on Immunisation are also expected to give their nod of approval soon after the group's final checks, which Mr Hunt said should see vaccines rolled out from January 10.

Prof Skerritt says the vaccine will be one-third the dose of the adult version but have the same vaccine molecule and will come in a different colour.

"We are confident in the safety of this," he said.

Australia will join a number of other countries that have started vaccinating children against COVID-19 or have approved its use.

The US has been rolling out this vaccine for about three weeks, Canada has started its rollout, while European countries and Israel have also approved it.

Australian Associated Press