A South Australian man who went to Victoria for work on the wharfs has tested positive for COVID-19, becoming the state's second active case in as many days.
The man in his 40s had initially tested negative when he flew back to Adelaide earlier in July, but a test on day 12 showed a strong positive result, Chief Public Health Officer Nicola Spurrier said.
The man had only mild symptoms but had lost his sense of taste.
He will be moved into hotel quarantine while his family members will self-isolate at home and be tested for the virus.
Professor Spurrier said while the case was worrying, she did not think it heralded the start of a second wave of COVID-19 cases in SA.
"Everything has worked well in this instance and my team has provided me with the confidence that we have got all the close contacts," she said.
However, it has prompted a review of the number of essential workers allowed to move between South Australia and Victoria.
"We really need to ensure that people are doing essential work at this time, particularly as the number (of cases) in Victoria continue to be of concern," Prof Spurrier said.
"As a country, we have been used to industries that work between states.
"But whenever you have a situation like this it's the right time to look at your practices and procedures."
Prof Spurrier said the heightened risk posed by Victoria was also a factor in the review along with the increasing number of people allowed to gather at major events in SA, such as AFL games.
The new infection takes SA's total since the start of the pandemic to 447.
It also came after SA Pathology conducted a record number of COVID-19 tests on Wednesday with 3364 samples analysed.
Health Minister Stephen Wade said an increased level of testing was vital to keeping the virus under control in South Australia rather than simply imposing tighter restrictions on locals.
"We will not beat this virus through a police state," he said.
"We fundamentally rely on South Australians continuing to work with us to keep them safe."