Three more cases linked to Adelaide cluster after medi-hotel at centre of SA outbreak evacuated

South Australia has recorded three more cases of coronavirus, linked to the growing cluster in Adelaide's north.

Health Minister Greg Hunt said these are all members of the same family cluster, and about 4500 tests had been conducted in the state to midday today.

Three Anglicare staff members have contracted the virus, and a number of schools have been closed.

Limits have been put on the purchasing of some products, including toilet paper, at major supermarkets, mirroring what happened in other states earlier in the pandemic.

Earlier, Premier Steven Marshall said the next 48-hours will reveal if a "catastrophic" coronavirus second wave will hit South Australia.

South Australia reported one new case overnight, in addition to the three this afternoon, and huge lines are forming at testing stations across the city and some wait times are blowing out to 11 hours.

Health teams this morning urgently evacuated everyone in quarantine at Peppers Waymouth Hotel, the source of the new cluster which has since spread into an aged care facility.

Everyone quarantining at Peppers is in the process of being moved to a new medi-hotel in Adelaide, where 9News understands they will once again begin 14 days of quarantine.

Staff at the hotel have also been put into quarantine, under orders of SA Health.

The single new case announced this morning is an employee at the Brompton Aged Care Home, in Adelaide.

READ MORE: How Adelaide's coronavirus cluster started and spread

9News understands another worker at the aged care facility is the subject of an inconclusive test, with more details expected later today.

Mr Marshall denied a hotel quarantine breach had leaked the virus into the community, but instead said "we believe it came from a surface".

The Adelaide cluster has been traced to Peppers Waymouth Hotel, where one of the cluster worked as a cleaner.

"So usually this (virus) is transmitted with droplets, aerosol droplets. This time we believe it came from a hard surface," Mr Marshall said.

SA Health believed the cleaner got infected with COVID-19 from a hard surface, Mr Marshall said, and not directly from contact with anyone isolating in the medi-hotel.

"The early investigation shows that it was transferred from the cleaner to the security officers."

With just one new case in the state, Mr Marshall said he woke up this morning to "a very different situation" than first feared.

LIVE UPDATES: The latest from the Adelaide cluster outbreak

READ MORE: One new COVID-19 case in SA as new restrictions now in place

But he was under no illusion that a huge wave of testing in the next two days would paint a much more accurate picture.

"We're hopeful that we've got this in time," he told Today.

"(But) we've still got an anxious 24 hours, 48 hours as all of the results come in."

SA Health teams have put 160 close contacts of the cluster into isolation, as all states and territories - except for New South Wales and Victoria - slammed borders shut.

Four cases at AnglicareSA's Brompton residential aged care home, which includes the potentially inconclusive test, in Adelaide are of great concern.

A second wave would be "absolutely catastrophic" for South Australia, Mr Marshall said, and so the advice was to "go hard, go early" with restrictions.

As of midnight, COVID restrictions were back in place in South Australia.

All international flights into Adelaide have been suspended and gyms and recreation centres are now closed.

Funerals, church services and weddings have capped limits, as do gatherings at pubs, clubs and restaurants, with a maximum of 100 allowed.

Mr Marshall said he was "very optimistic" that today's single case showed SA was in a good position.