Qantas staff at Adelaide Airport were directed to continue working after it was discovered they had been exposed to the coronavirus, the transport union says.

Key points: The Transport Workers' Union says Qantas knowingly exposed staff at Adelaide Airport to coronavirus

The Transport Workers' Union says Qantas knowingly exposed staff at Adelaide Airport to coronavirus Qantas maintains it has fully complied with SA Health's directions

Qantas maintains it has fully complied with SA Health's directions A staff member at an early learning centre was one of two new confirmed cases in SA on Monday

However the aviation giant maintains it has vigilantly monitored the situation and is working with the Government to stop further spread of the virus.

SA Health ordered 750 employees into quarantine in an attempt to contain a cluster of cases linked to the airport, including 18 baggage handlers, three other workers and 13 close contacts.

The Transport Workers' Union (TWU) says it is compiling evidence Qantas "knowingly exposed" workers to the virus after it was made aware of the first confirmed case.

Union bosses claim the company was late to act, downplayed the risk to staff and failed to implement proper safety measures.

"We're being told Qantas staff were directed to attend work, [they] were concerned about their health and safety, but they went to work," South Australian branch secretary Ian Smith said.

"Some of them have become infected and they've infected their families — that's disastrous and totally unsatisfactory and that could have been stopped."

Mr Smith said SA Health stepped in after Qantas took a "blasé" approach to managing the issue.

"SA Health don't trust the information they're receiving from Qantas to make such a drastic decision," he said.

The quarantine order applies to employees who have worked in certain areas of the airport since March 17, and affects cabin crew, pilots, customer service staff, engineers and baggage handlers.

In a statement, Qantas said it has complied fully with SA Health's directions.

Transport Workers' Union SA branch secretary Ian Smith says Qantas staff went to work despite safety fears. ( ABC News: Shuba Krishnan )

"Unfortunately, a few weeks ago one of our baggage handlers at the airport entered the workplace while infectious and unknowingly passed the virus to others," it said.

"Any employee identified as needing to self-isolate through SA Health's contact tracing process has been immediately directed to do so."

The airline said it has upheld a strict coronavirus cleaning protocol which includes disinfecting work and break areas.

Adelaide Airport also released a statement saying it will continue to assist Qantas and SA Health with all of their ongoing coronavirus investigations, and has undertaken a range of protective measures.

The Australian Services Union, which also represents Qantas staff, called on the company to look after those employees sent into isolation.

Scott Cowen, South Australian branch assistant secretary, said Qantas has reversed an earlier decision not to pay staff who were required to self-isolate.

"We've since been informed that employees directed to self-isolate would be paid as normal," he told ABC Radio Adelaide on Monday.

"We're working with the company to determine what normal means, because obviously these are not normal times at all."

Union members are also calling on the company to provide accommodation for employees directed to self-isolate, in an effort to ensure family members are not put at risk.

Mr Cowen said some of the 750 staff could be based at other airports but have travelled to Adelaide, or could work for subsidiary companies of Qantas.

The state's chief public health officer said the employees who tested positive to the virus were not in areas of the airport accessible to the general public.

School staff member among two new cases in SA

SA Health confirmed two new coronavirus cases on Monday, taking the state total to 431.

One of the new cases is a staff member at St Peter's Girls' School, prompting authorities to order 10 children and four other staff members into quarantine.

Deputy chief public health officer Mike Cusack said while the state has recorded some "very positive" results, the virus has not been eradicated.

"It would be wrong to imply [that] we're over the back of this and we've seen the worst," Dr Cusack told reporters.

"We're determined to try to clear the virus [from] South Australia."

Premier praises public for staying home over Easter

South Australian Premier Steven Marshall extended a "grateful thanks" to the community for staying away from the state's regions, which are usually tourist hot spots over Easter.

"I will just say that we are pleased that the people of South Australia have really listened to the requests from regional mayors, regional communities to stay out of the regions this Easter," he said.

"We still, of course, have one day more of the Easter break, but it's fair to say, in speaking to the mayors today, they are delighted with the response of the people of metropolitan Adelaide, the people of SA, who haven't spent their Easter away in regional communities.

"Of course, this is devastating on regional communities' economies, but it's just so important at this time, to adhere to all of those restrictions.

"So I say a grateful thanks to the people of South Australia for making sure that we can slow the spread of this disease."

Mr Marshall said despite the drop in new coronavirus cases, it was "way [too] premature" to talk about easing restrictions.

Authorities in the coastal town of Victor Harbor, which normally sees its population inflate significantly over the Easter weekend, praised people for staying away.

"Fabulous to see our wonderful community, including our ratepayers who usually live out of town, following our requests to socially isolate," mayor Moira Jenkins posted on Facebook.

"Thank you all for not treating this as a normal Easter. I have never seen Victor so empty. Well done."

Police Commissioner Grant Stevens said the level of compliance with restrictions and isolation requirements has been "quite exceptional".

He said police had so far checked in with more than 640 people to ensure they were isolating and "almost all those people were compliant".

Officers have issued 10 expiations and seven cautions to the public, and found two businesses in breach of the regulations.