In the state of South Australia, the government announced a six-day lockdown on Wednesday (November 18) to stamp out a new coronavirus cluster, which has now grown to over 20 cases.
It's put Australia back on high alert, after neighboring Victoria state emerged from its own lengthy lockdown earlier this month.
As of midnight, all South Australian schools, takeaway food, pubs, cafes and universities will be closed for business, along with the construction industry, which had been allowed to operate as usual during past lockdowns in the country.
State Premier Steven Marshall described the lockdown as a crucial "circuit breaker," while medical experts raced to trace the latest virus strain.
"Our concern is that if don't have this circuit breaker that we will not stay ahead of this. There is no second chance to stop a second wave."
The new outbreak is linked to an Australian who arrived in the state capital, Adelaide, from overseas and entered mandatory quarantine in a hotel.
Hotel workers are believed to have contracted the virus after touching a contaminated surface.
South Australia had previously gone without a local transmission of the virus since October 31.
Meanwhile Victoria, Australia's previous virus hotspot, clocked its 19th straight day of zero news cases.