A similar result was recorded on Sunday with both related to catchment areas covering Adelaide’s CBD.

It’s possible the results have come from old cases of the virus among people in the city’s quarantine hotels, but authorities have urged anyone who visited the CBD in the past week to get swabbed if they have even the mildest of symptoms.

“It’s really important that we do remain alert in the community,” Deputy Chief Public Health Officer Emily Kirkpatrick told reporters on Tuesday.

“While we’re not saying that there’s any indication that there is community transmission here in South Australia, it is really important that if you are out and about that you do get tested if you have even the slightest of symptoms.”

Kirkpatrick said SA was also checking with other states on the movement of people across the border in recent weeks to see if they correlated with anyone who had recently recovered from having the virus.

Average daily testing rates across SA are just above 2500 this week, with the lower number causing some concern among health officials with the Festival Season in full swing.

SA reported two new cases of COVID-19 on Tuesday: one from a teenage girl and one in a man in his 60s – both of whom are quarantining in a medi-hotel.

SA has also administered almost 4000 vaccinations since the rollout began two weeks ago, although this is still well short of the 12,000 forecast to be completed at the end of the week.

Prime Minister Scott Morrison has reaffirmed the federal government’s commitment to offering every Australia a vaccine by the end of October, despite expert scepticism over whether this goal can be reached.