Premier Steven Marshall this afternoon fronted the media for a second time today, after earlier telling the public the cluster that began with a case detected at Modbury Hospital had grown to six cases.

Just five hours later however, it had grown to 12 – including five who attended the “high risk site” Tenafeate Creek Wines at Yattalunga on Sunday between 1.45pm and 4.30pm.

“We don’t usually have two press conferences in one day, but unfortunately we have new cases and concerning new exposure sites,” Marshall said.

“We go from six to 12 cases.”

Another new case – a young child aged under five years – has been linked to The Greek on Halifax restaurant in the city.

Marshall said “most concerning” was a new exposure site, the Gawler & District College B–12, which was attended by one of the five new cases linked to the winery on Monday morning, before he was notified by SA Health and went into quarantine.

Chief public health officer Professor Nicola Spurrier said both the winery and the restaurant gatherings were now considered “super-spreader events”.

“I would say that both the Greek on Halifax and this winery are examples of super spreading events,” she said.

“This is presumably a very busy winery and we know The Greek on Halifax also had a busy night on Saturday night. People in SA do need to prepare themselves for more cases, that’s certainly my expectation.

“It is very serious. I am concerned. I am also very pleased we were able to put a lockdown in place very quickly.”

Marshall said: “This is exactly and precisely why we needed to move SA to the new lockdown restrictions.”

“It would have been a very difficult situation if these six new cases were out and about in the community,” he said.

“This disease thrives on indecision – we’ve gone hard and we’ve gone early.”

Spurrier said while “people need to prepare themselves for more cases”, it was “very difficult to say” whether the mooted seven-day lockdown would be extended.

The new cases linked to the Tenafeate Creek Winery are a woman in her 50s, a man in his 50s, a woman in her 60s, a man in his 40s and a woman in her 80s.

Spurrier said she was concerned because their exposure was “fairly recent” and all had already returned positive tests, showing a lag time of as little as 24 to 36 hours between exposure and being infectious.

However, all five were notified of their potential exposure via secondary contact tracing on Monday night, and have been in quarantine since then.

The man in his 40s attended the Gawler school on Monday morning, according to Spurrier.

“We’re very worried about the timing between the exposure and these people testing positive,” Spurrier said.

“The most important time will be on Monday before these people went into quarantine.”

Earlier today South Australia entered its first day of lockdown after recording a new case overnight – a woman in her 20s who was working at The Greek on Halifax exposure site in the city, and who is also a staff member at Westminster School in Marion.

Dozens more exposure sites have now been added to the growing list, including Westminster School, Burnside Shopping Centre at Glenside, Tea Tree Plaza Shopping Centre at Modbury, St Ann’s College at North Adelaide, Whistle and Flute café at Unley, McDonalds at Felixstow and Woolworths at Marryatville.

The Westminster School case had attended on Monday, a pupil free day, for a teacher-training session. 

The woman provides counselling to boarders at the school and authorities are now checking if any were exposed to the virus.

She also went shopping at Burnside Village on Sunday.

Emergency financial help is also being made available to South Australians affected by the shutdown, with the Commonwealth announcing payments for people in Adelaide and the State Government announcing support for people in the regions.

The cluster began when an 81-year-old man tested positive at Modbury Hospital on Monday morning.

His daughter and other close contacts in the north-eastern suburbs later tested positive, with one of those exposing diners at the busy Halifax St restaurant on Saturday night.

Spurrier said genomic testing from the 81-year-old matched with the New South Wales Delta outbreak.

The man did his 14-day quarantine period in NSW after returning from Argentina, before arriving in Adelaide on July 8 and spending more than a week in the community before developing symptoms and testing positive.

Spurrier late today announced the establishment of a new COVID-testing clinic dedicated to high-risk cases – in a location she declined to disclose, despite questions about a new site at Lot Fourteen – as people seeking tests were forced to queue for several hours at stations across Adelaide.

Other new exposure sites identified today include the Modbury Centrelink on Friday for two hours from midday, Chiera & Sons Fresh Market at Salisbury Downs on Sunday afternoon and Gym24Seven at Para Hills West late on Monday.

Spurrier said her message to the public is now is “a time to stay at home and not move”.

“If you don’t need to go out, don’t go out,” she said.

“I know we have reasons to leave the home but just minimise those reasons…

“Try and relax, think of some hobbies to do: as I said to my husband when I left home this morning – this is the day you can tidy up your sock drawer.”