The impact of vaccines on the Omicron variant will be clearer within days, one of Australia's top doctors says.
Health Department officials have also told Parliament's COVID-19 committee they expect to offer a first dose to every five-to-11-year-old in Australia by the start of the school year.
Chief medical officer Paul Kelly on Tuesday revealed there were 37 confirmed cases of the highly infectious Omicron variant in Australia, 27 of which were locally acquired.
Professor Kelly said there were "no definite signals" Omicron was more severe than previous variants, but confirmed it was at least as transmissible as Delta.
He accepted mutations in the variant posed a "theoretical concern" over vaccine efficacy, predicting investigations would produce preliminary advice "within the next few days".
"There does, however, appear to be anecdotal evidence that reinfection with Omicron is occurring," he said.
"I understand that these changes may be worrying us for some Australians, but I wanted to give you reassurance about how well prepared Australia is and how we are responding.
"We still need to learn much more about Omicron. The amount of information we are seeking and receiving from our partners around the world is significant."
Other treatments - corticosteroids, receptor blockers, and some antivirals - would still prove effective, he said.
Health Department secretary Brendan Murphy said Australia's deal with the two companies covered any future adaptions required.
"[But] we simply don't know whether we will need a different vaccine until we get the data on Omicron with the current vaccines," he said.
COVID-19 taskforce commander Lieutenant-General John Frewen also revealed all five-to-11-year-olds were expected to be offered a first dose by the start of the 2022 school year
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The Therapeutic Goods Administration confirmed the Pfizer vaccine was safe for the cohort over the weekend. General Frewen said the Commonwealth was working with the states and territories over models for school-based vaccination programs, but supply would prove no issue.
"But at the moment, we think we will have the capacity to get all of that cohort [a] first dose very early in the new year," he said.
Professor Kelly said adverse events in children were "exactly what you'd expect", and in line with those experienced by adults: pain in the arm, fatigue, body aches, and fever.
He said Australia had been "cautious" in monitoring vaccination child vaccination in the US.
"They've been following very closely and carefully for vaccine side-effects and not really found anything severe at all," he said.