South Australia to offer Pfizer and AstraZeneca vaccines to over 16s in Australian first

South Australia has announced a major step forward in its vaccination rollout, offering both Pfizer and AstraZeneca to anyone aged over 16.

Bookings for the two vaccines will be available at state-run clinics from Monday.

The state will become the first in Australia to make both vaccines an option for those over 16.

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Premier Steven Marshall said as of Monday, 127,000 extra booking slots would open to give younger South Australians the opportunity to get vaccinated.

"As of Monday everyone over the ages of 16 can book in for that vaccination," Mr Marshall said this morning.

"We know that (vaccination) is what is going to keep our state safe, and it's our passport out of the situation that our country currently finds itself in."

Mr Marshall conceded the availability of mRNA vaccines would be a constraint and the appointments would be for September and October, when Pfizer supplies become available.

"We're wanting to increase the demand now, get those bookings into the system," he said.

"Of course there are going to be delays because we do need to wait for additional supplies."

He encouraged people over 40 to get their bookings in before Monday, when they will have to compete for booking slots with the younger cohort.

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It comes as South Australian health authorities have defended a decision to enforce a double quarantine period of athletes returning from the Olympics.

Australian athletes currently quarantining in Sydney will have to undertake a second 14-day quarantine period on arrival in Adelaide.

The extra 14 days was imposed after last month after a returned traveller from Argentina contracted COVID-19 in Sydney and sent South Australia into lockdown.