Police visited a Dunedin property last night after it became apparent that instead of cancelling a party after contracting Covid-19, the occupants intended to hold a "Covid-positive party". 

Dunedin Senior Sergeant Anthony Bond said police visited the Leith St North address at 6pm. 

The occupants were planning a "Covid-positive party" involving all their friends who had the virus, he said. 

"Police advised them that this is a stupid idea." 

Meanwhile, student Seraphine Ruch's first few days at university have not quite gone how she expected. 

The 17-year-old arrived in Dunedin last week from Wellington, excited to begin her first year of study at the University of Otago. 

But what should have been the rushing rapids of the first week of university life has subsided into a pool of isolation. 

On Tuesday she learned she had had contact with a close contact of a Covid-19 case. 

She went to the Malcolm St testing centre for a PCR test and was given a rapid antigen test instead. 

When she took the test and saw two red lines appear under a C and a T, she knew she had Covid-19. 

Ruch is one of hundreds of University of Otago students isolating as an Omicron wave sweeps through Dunedin. 

She has taken the university's advice and remains mostly in her room on the seventh floor of University College's (UniCol) residential building. 

"I'm not allowed to go in the common room or outside. 

"It's okay for now, but I'll be isolating for 10 days, and in a few days I might feel differently," Ruch said. 

She said she had received a bag containing hand sanitiser, tissues, masks, gloves and a rubbish bag for meal containers. 

Breakfast was delivered every day between 8.40am and 9.30am, lunch at 11.45am, and dinner was at 5pm, she said. 

She is eligible for the care packages the university and the Otago University Students Association have begun distributing. 

Ruch, who is enrolled in a health sciences programme, said she kept busy by reading science articles about, among other things, experiments concerning nuclear fusion in laboratories. 

She had also been telephoning friends. 

"I've been in touch with seven friends, and they all have Covid-19," she said. 

Ruch, who is too young to receive a booster, was taking her positive result in her stride. 

A university spokeswoman said several hundred students have Covid-19 in North Dunedin. 

She said many hundreds more were self-isolating because they were close contacts of someone who had tested positive. 

"We are pleased with the large number of students who have gone to get tested. 

"The vast majority are doing the right thing and self-isolating," the spokeswoman said. 

One in five Covid-19 tests taken in Dunedin is returning a positive result, a rate that has shocked epidemiologist Professor Michael Baker. 

"I don't know if it's a national record but those are very high rates," Baker, of the University of Otago, said yesterday. 

Overall, across Otago and Southland the percentage of Covid-19 tests returning a confirmed diagnosis of the disease sits at 16.5 per cent. 

Baker said a positivity rate of 5 per cent 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 per cent. 

The southern figures — and especially the Dunedin positivity rate of 21.6 per cent — were very high, 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, 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, had a positivity rate of 10.5 per cent, Southern District Health Board medical officer of health Dr Susan Jack said, while the Invercargill rate was 6.6 per cent. 

"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," Jack said. 

Testing facilities and laboratories processing 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 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. 

After research by SDHB staff, the Ministry of Health reclassified hundreds of cases reported as being elsewhere but actually being people in the south. 

That, on top of new positive tests, accounted for the large hike in Covid numbers locally. 

"It is important to note that a case undercount anywhere in the country does not significantly impact our assessment of the outbreak, public health decision-making or public health advice," a ministry spokesman said. 

"With Omicron spreading quickly in New Zealand, people shouldn't rely on case numbers to take action to prevent them catching and spreading Covid-19." 

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 were in the southern region.