Image of the Sydney Opera House. The sails of the iconic Sydney Opera House were lit up in red on Thursday night to mark the beginning of the Chinese Lunar New Year. Photo via Twitter

 A two-week-old pandemic lockdown in Australia’s biggest city is being extended for another week due to the vulnerability of a population largely unvaccinated against the coronavirus.

New South Wales state Premier Gladys Berejiklian said Wednesday that health experts recommended pushing the lockdown in Sydney on to midnight July 16.

The decision means most children in Sydney and some nearby communities will not return to school next week following their mid-year break.

Only 9% of Australian adults are fully vaccinated, heightening fears that the delta variant of the coronavirus could quickly spread beyond control.

There have been more than 300 coronavirus infections in Sydney linked to a limousine driver who tested positive June 16. He is thought to have been infected while transporting a US flight crew from the airport.