Covid-19 has returned to the South — almost 22 months since the last community transmission case.

Late last night, health officials confirmed a person in Dunedin had tested positive for Covid-19, and that during their infectious period they had also been in Wanaka and Cromwell.

The announcement came just hours after news that two Queenstown residents had tested positive for the virus, cases which are likely to be the highly transmissible Omicron variant of the disease, although testing had yet to confirm that.

Otago and Southland’s last community transmission case was recorded on April 17, 2020.

Officials also revealed yesterday that at least one person from a group of North Island visitors to Queenstown last weekend had since tested positive to Covid-19.

Southern District Health Board medical officer of health Dr Michael Butchard said anyone from Dunedin, Wanaka or Cromwell should regularly check the Ministry of Health website for new locations of interest.

None had been posted for Dunedin or Wanaka last night, although a petrol station in Cromwell had been listed.

The Dunedin case was now isolating at home, Dr Butchard said.

"Investigation into the source of this case is ongoing".

Both the Te Kaika vaccination centre in St Kilda and the WellSouth Covid community testing centre in Malcolm St offer free walk-in and drive-through Covid-19 testing.

Earlier, a raft of locations of interest in Queenstown were notified by the Ministry of Health.

Many, including several popular restaurants and bars, were noted as close contact locations.

Dr Butchard said it was possible the two Queenstown residents had caught Covid-19 from an infected person in the tourist group, but as yet there was no epidemiological evidence to show a connection between them.

"We don’t have enough links to be definitive on that.

"We may need to rely on the whole genome sequencing to be able to make that link."

The two Queenstown cases, the infected resident and a household contact, had stayed at home as soon as the first case started to show symptoms, Dr Butchard said.

"There is no-one else in that household ... The household contact doesn’t have any symptoms but they are positive as well."

As soon as the first person in the household felt ill they mostly stayed at home and were tested on Tuesday, Dr Butchard said.

They had possibly been infectious at the weekend, but Dr Butchard said they had done the right thing in staying home and getting tested as soon as possible.

Not every location of interest in Queenstown was connected to the local case, and several were logged in relation to the group of visitors, who are understood to have undertaken a variety of adventure and tourism-related activities while in the resort.

There was a slight increase in testing numbers in Queenstown yesterday following the announcement of the cases.

Te Kaika’s testing centre in Frankton experienced an increase in demand for testing about half an hour after it opened.

Te Kaika systems innovation manager Raewyn Nafatali said even though they were busier, numbers still were not particularly high.

"On an average day they do up to about 15 [tests], and today so far they’ve done about 50," she said.

Queenstown Medical Centre chief executive Ashley Light said testing was steady at the medical centre yesterday.

"Anyone who has been a close contact with the identified positive case has come through, as opposed to people who felt they had symptoms, so we have had a slight increase [in testing] but nothing that the system’s not able to cope with," Mr Light said.

Overall, 155 tests were carried out in Queenstown, primary health organisation WellSouth said.

"While this is more than double most weekdays for this month, it is still fewer than we would like to see," WellSouth chief executive Andrew Swanson-Dobbs said.

Mr Swanson-Dobbs said there was plenty of testing available, it was free and there were two sites in Frankton — the Engage Safety Covid-19 Testing Centre and Te Kaika — where no appointments were required.

Dr Butchard said no additional resources had been devoted to the Queenstown cases as yet.

"Anyone who has even mild cold symptoms, even the mildest scratchy throat, please get tested as these are the most common signs of infection," he said.

"Also, if people need a wake-up call or another reason to get a booster shot [of the Covid-19 vaccine] this should be it, as there is a large benefit in protection from being boosted as opposed to having had two vaccination doses, and there is solid evidence on that."