The woman in her 20s volunteered to help with testing operations in Melbourne associated with the current surge in cases there.

She returned to Adelaide on Wednesday and is now in isolation along with one close contact.

Other health officials who went to Melbourne as part of the same team have all tested negative so far.

Chief Public Health Officer Nicola Spurrier said the woman had followed all the proper procedures with protective equipment but an infection in such circumstances was "part of the risk of this sort of work".

"She absolutely followed the correct infection control processes," Professor Spurrier said on Friday.

"But this is risky business."

It was also revealed that 170 people were expected to arrive in Adelaide on Saturday on a repatriation flight from India.

All will go into hotel quarantine with officials expecting at least some to have COVID-19.

At the same time, Police Commissioner Grant Stevens rejected calls from the state opposition to check every car and truck coming into SA from Victoria and conduct mandatory border testing.

Mr Stevens said regardless of the resources available, stopping every truck would cause significant delays with road freight and create significant road safety issues.

The commissioner also expressed disappointment over the good behaviour bond imposed on a 65-year-old Mt Gambier woman who snuck back into SA from Victoria by hiding in a truck on Tuesday night.

She appeared in court on Friday and pleaded guilty to failing to comply with a direction.

The 46-year-old driver of the truck was also arrested in Adelaide and charged with failing to comply with a direction and was expected to appear in court on Monday.

Mr Stevens said the general sentiment in the community towards those who breached the state's border rules was "one of disgust".

"People recognise we have a significant concern right on our doorstep with Victoria in the current state it's in and we're doing as much as we can to protect the South Australian community," he said.

"People who breach these directions are putting other people at risk and they're making a mockery of the efforts of everybody in the community to work through this COVID-19 situation."

Premier Steven Marshall said in light of the dangerous situation in Victoria and the clusters of cases in NSW, SA would not change its current border rules.

Under the current provisions, only essential travellers are allowed to enter SA from Victoria.

But people can come from NSW and the ACT provided they quarantine for 14 days.

The new coronavirus infection in SA on Friday takes the total number of cases diagnosed in SA since the start of the pandemic to 450 but only three of those are considered active infections.

Australian Associated Press