Australia's hope of returning to "Covid zero" suffered a fresh blow Friday, as Sydney reported another record number of new infections and authorities warned residents to brace for worse to come.

For a second straight day, New South Wales premier Gladys Berejiklian said Australia's most populous state hit a new peak with 291 cases detected.

A health worker takes a swab sample from a resident in the Chinese city of Wuhan, which WHO experts visited in a attempt to discover the orgins of the Covid-19 virus
A health worker takes a swab sample from a resident in the Chinese city of Wuhan, which WHO experts visited in a attempt to discover the orgins of the Covid-19 virus AFP / Hector RETAMAL

"At least 50 of those were infectious in the community," Berejiklian said, foreshadowing more cases to come, despite a lockdown that is now in its sixth week.

"I'm expecting higher case numbers in the next few days, and I just want everybody to be prepared for that," she said.

Roughly 60 percent of Australia's 25 million residents are currently in lockdown, as the country tries to curb the spread of a virulent Delta variant outbreak.

Melbourne is back under lockdown for the sixth time this pandemic
Melbourne is back under lockdown for the sixth time this pandemic AFP / CON CHRONIS

Melbourne became the latest major city to shutter late Thursday, after Victoria state premier Dan Andrews issued stay-at-home orders for the sixth time in this pandemic.

"To be really frank, we don't have enough people that have been vaccinated and, therefore, this is the only option available to us," he said.

Downtown Melbourne is nearly deserted with the city under lockdown as Victoria state premier Dan Andrews said it was the 'only option' due to the low vaccination rate so far
Downtown Melbourne is nearly deserted with the city under lockdown as Victoria state premier Dan Andrews said it was the 'only option' due to the low vaccination rate so far AFP / Con Chronis

Barely 20 percent of Australians have been fully vaccinated, due to an acute lack of supply and pockets of vaccine hesitancy.

With cases rising and lockdowns seemingly able to slow, but not stop the spread, there are growing questions about whether Australia can return to the "Covid zero" status it enjoyed for much of the last 18 months.

"Given where numbers are, given the experience of Delta overseas, we now have to live with Delta one way or another, and that is pretty obvious," said Berejiklian.

She said returning to zero cases would be "a challenge" but "that has to be our aspiration, we have to try to get down as low as we can."

Meanwhile, there are signs that Australians are tiring of on-again-off-again restrictions that have marked pandemic life, although compliance with lockdown rules is still widespread.

"I'm not saying we're doing super well but we're keeping our heads above water," Melbourne market trader Linda told AFP Friday.

"I'm starting to feel like today it's starting to hit me harder than any other lockdown. Hang on, I haven't seen my family for such a long time."

Coronavirus