It comes as SA Health ordered about 10 workers at the Queen Elizabeth and Royal Adelaide Hospitals home today in relation to a confirmed COVID-19 case reported yesterday.

Chief public health officer Nicola Spurrier this afternoon said that the wife of the man aged in his 40s, who travelled from Victoria to South Australia as an essential worker, works at one of the public hospitals on its switchboard.

She said another person, who works at the other hospital on its switchboard, visited the house where both are quarantining on Monday and reported experiencing COVID-19 symptoms.

Spurrier said that person had tested negative for COVID-19, but SA Health would conduct a second test today.

SA Health is also waiting on results from the other close contacts of the confirmed case, which are expected to come back today.

Spurrier said there was a “low risk” to patients and other staff at the QEH and RAH, and SA Health was taking a “very, very cautious” approach.

“We have split shifts, so it’s not going to have any impact on the hospital,” she said.

“We are continuing to do quite a lot of forensic work and interview work around this particular case to make sure that we’re absolutely getting to the ends of any potential chains of transmission.”

Meanwhile, Premier Steven Marshall said this morning’s transition committee meeting decided to extend South Australia’s hard border closure with Victoria by banning all arrivals into South Australia from midnight Tuesday.

Previously, South Australian residents were exempt from the ban.

It is up SAPOL to determine whether a person has “significant” reasons to make an exemption for them to travel into SA.

Travellers arriving into South Australia from New South Wales will still be required to quarantine for 14 days, as the eastern state continues to battle with three COVID-19 clusters.

Marshall said no dates have been set on when the New South Wales or Victorian border restrictions would be lifted.

South Australia will also reintroduce restrictions on gatherings from midnight Tuesday, including a cap of 50 people at home gatherings and 100 people at weddings and funerals.

“The entire nation now is on high alert,” Marshall said.

“There are currently in excess of 100 outbreaks in Victoria (and) this is of great concern to us, most importantly of concern is the vast majority of the cases which have been identified in recent weeks are still under investigation.

“We want to be absolutely certain that we do everything we can to protect the health of South Australians but also the economy.

“We do not want to go backwards, we do not want to be putting harsh restrictions, lockdowns, back in place, so we’ve got to work hard, we’ve got to protect that border and we’ve got to make sure that South Australians continue to get tested.”

SA Police Commissioner Grant Stevens said the measures send a “very strong signal” about the level of concern that COVID-19 could make its way back into South Australia from the virus-affected Victoria, which today recorded another 300 new cases and six deaths.

“It sends a message that people should not be complacent,” he said.

Stevens also announced that as of midnight tonight, businesses that do not have COVID-safe plans in place, or that are not complying with their plans, will be forced to close until they are able to demonstrate that they are capable of complying.

“We know that there are businesses that are taking a very liberal approach to their COVID-safe plans,” he said.

“We will take a more stricter approach.”

However, Spurrier said larger crowds would be allowed at this weekend’s SANFL matches after SA Health approved seven COVID management plans.

She admitted it might not sound fair compared to other restrictions, but “football is outside so that’s lower risk”.

SA Health has received over 100 applications for COVID management plans, but 60 of those are deemed “high risk” and are currently on hold.

South Australia has recorded 447 COVID-19 infections since the start of the pandemic, three of which were identified this week.

Meanwhile, South Australia’s emergency declaration will be extended for a further 28 days from tomorrow – the fourth such extension since March 22.