SYDNEY - A sudden coronavirus cluster emerged Monday in an Australian city that had gone seven months without a significant outbreak, with the virus again escaping from the country's hotel quarantine system.
South Australia state reported four cases had been detected in Adelaide on Sunday, before the cluster grew sharply overnight to 17 people Monday -- the largest there since April.
"We just kept getting positives coming off the machine," chief health officer Nicola Spurrier told public broadcaster ABC.
Spurrier said it was "very clear" the cluster was linked to a hotel used to quarantine travelers returning from overseas, where one of the infected people works.
"We haven't got the genomics yet, but I'm absolutely certain it has come from a medi-hotel," she said.
Officials moved quickly to contain the outbreak, ordering hundreds of people to isolate while closing linked schools and businesses.
South Australia last detected a Covid-19 cluster outside border quarantine in August, when health authorities swiftly prevented the small handful of cases spreading using similar measures.
But there are fears the latest outbreak has the potential to infect high-risk populations, with a prison guard and aged care workers reportedly among those testing positive.
It comes just as Australians were breathing a collective sigh of relief after squashing a second-wave outbreak in Melbourne that originated from security bungles at hotel quarantine.
Melbourne, which recorded thousands of cases and hundreds of deaths in recent months, has now gone more than two weeks without a single new case.
The country's internal borders are due to be almost fully reopened by Christmas, but the Adelaide cases prompted other states to immediately impose new restrictions on anyone travelling from South Australia.
Overall, Australia has been relatively successful in containing the virus, with just over 27,700 cases and 907 deaths recorded since the pandemic began.
© Agence France-Presse