The Pfizer vaccines shipped from Poland have been approved for Australians by the Therapeutic Goods Administration.
The million doses of the vaccine landed in Australia last night.
"These doses are all from one batch of the vaccine produced from the same plant in Europe as other doses of this vaccine imported directly by Pfizer Australia," the TGA said in a release.
"The TGA has reviewed all batch release and transportation (and) cold chain documentation as satisfactory for release."
The extra doses are set to be rolled out from as early as next week.
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"We have been in discussions with the Polish government now for several weeks, and we have secured over an additional one million doses of Pfizer, which will start landing in Australia from tonight," Prime Minister Scott Morrison said.
The new doses are on top of the 40 million Pfizer doses that Australia has already contracted to be delivered.
"And of course, we will be ramping up again significantly in the fourth quarter of this year," Mr Morrison said.
"These one million doses, will give hope to people right across the country, particularly in New South Wales where they are fighting this Delta strain in the most significant battle we have had in this country during the course of the COVID-19 pandemic up until now."
Mr Morrison said the newly secured doses will be targeted toward 20- to 39-year-olds.
"(They) were identified in the Doherty modelling as peak transmitters of COVID-19," he said.
"Some of those doses will be prioritised for express delivery to the 12 government areas where the COVID-19 outbreak continues to grow.
"This allocation is based directly on the advice I received from the Chief Medical Officer, Professor Kelly."