"I don’t know if it’s a national record but those are very high rates," Prof Baker, of the University of Otago, said yesterday.
Overall, across Otago and Southland the positivity rate — the percentage of Covid-19 tests returning a confirmed diagnosis of the disease — sits at 16.5%.
Prof Baker said a positivity rate of 5% was regarded by the World Health Organisation as being likely to show that an epidemic was under control, and that yesterday the national positivity rate had just passed 10%.
The southern figures — and especially the Dunedin positivity rate of 21.6% — were very high, Prof Baker said.
"That suggests a widespread outbreak and suggests that if you did more testing you would find a lot more cases."
The high southern positivity rate emphasised the urgent need for anyone who had not been vaccinated or who had not received a booster jab to get one, Prof Baker said.
"This would have been devastating without vaccination ... I’m still amazed at the million or so New Zealanders who have the option to get a booster and still haven’t done so.
"This is a very serious illness which may not kill you but which can certainly make you miserable for several days."
Queenstown, the other centre in the South with major numbers of cases in the current outbreak, had a positivity rate of 10.5%, Southern District Health Board medical officer of health Dr Susan Jack said, while the Invercargill rate was 6.6%.
"If people have been in contact with a known case and have symptoms, please assume you have Covid and isolate even if your test result has not come through yet," Dr Jack said.
Testing facilities and the laboratories processing those swabs have been under severe pressure throughout the region this week, and on Tuesday almost 2800 tests were taken.
That had led to delays in processing results, some people having been told they might need to wait five days to learn if they had Covid-19.
On Tuesday the Southern region began more widespread use of rapid antigen tests, which Dr Jack said should ease pressure on laboratories.
"There has been a delay in getting out some results of up to three days but generally results are coming through within two and a-half days.
"If you test positive on a Rat test you do not need to have that confirmed by PCR — you are a case."
The high positivity rate was further demonstrated by the record 455 new cases reported in the southern district yesterday.
More schools in the region reported cases, including Taieri College and St Hilda’s.
On Tuesday the Southern District Health Board revealed that case numbers in Otago and Southland were likely to be twice as many as officially released because people registered to GPs in other regions were being counted in other provincial tallies.
Of the 455 cases announced yesterday, 136 were in locations yet to be confirmed, but 233 were in Dunedin, which had a total of 584 active cases.
Queenstown Lakes reported an additional 59 cases, and every region other than Southland also reported new cases.
Nationally 3297 community cases of Covid-19 were reported yesterday. 179 people were in hospital with the disease, although none of those cases were in the southern region.
Current cases
Southern District
Total new: 455
Total active: 1145
Central Otago
Total new: 2
Total active: 13
Clutha
Total new: 3
Total active: 4
Dunedin
Total new: 233
Total active: 584
Gore
Total new: 1
Total active: 8
Invercargill
Total new: 14
Total active: 43
Q’town-Lakes
Total new: 59
Total active: 329
Southland
Total new: 0
Total active: 8
Waitaki
Total new: 7
Total active: 20
TBC
Total new: 136
Total active: 136
Source: Ministry of Health 11.59pm February 22.
