Christchurch's only coronavirus cluster of 10 or more cases is amongst the city's most vulnerable population; in a rest home.

The revelation came after Prime Minister Jacinda Ardern condemned a man who videoed himself allegedly coughing deliberately over fellow shoppers in a Christchurch supermarket as "an idiot".

A total of 86 people have coronavirus in the Canterbury District Health Board area, including the district's first cluster of 10 or more cases.

A health board spokeswoman said the cluster was linked to a residential care home, but would not name the facility.

The owner of a Spreydon rest home, where two residents were confirmed positive for covid-19 last week, denied it was the site of the cluster.

On Thursday, one resident at the George Manning Lifecare and Village in Spreydon tested positive, while a second test returned positive for the virus the following day. However, on Sunday Heritage Lifecare group chief executive Norah Barlow said she was confident the city's only cluster was not linked to the facility.

IAIN MCGREGOR/STUFF One case was confirmed at the George Manning Lifecare and Village in Spreydon on Thursday, and another test came back positive on Friday.

A handful of other residents had been tested for the virus, but none had come back positive since Friday, she said. The residents who had earlier tested positive were "thankfully doing well", she said.

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"I just keep hoping it's a light dose because so far they're really doing well. We all know older people are more vulnerable so we're just keeping our fingers crossed that they'll be okay."

Barlow earlier said the company was lucky to have had PPE stocks in place before the coronavirus outbreak, which meant they were prepared.

A previously reported cluster of eight cases connected to Christchurch compost firm Living Earth does not meet the current threshold for a "cluster" of 10 or more cases.

Despite, 20 new cases confirmed publicly in Canterbury on Sunday the rate of coronavirus in the Canterbury DHB remains relatively low at about 15 cases per 100,000 people. There are no patients in Canterbury hospitals.

Jacinda Ardern criticises 'idiots' breaking lockdown rules.

Canterbury's rate is less than half that of the Waikato District Health Board where there were about 35 cases per 100,000 people and well below the Southern District Health Board rate of 49 cases per 100,000, largely due to a cluster associated with a wedding in Bluff.

On Monday, a 38-year-old man will appear in Christchurch District Court charged with endangering life by criminal nuisance and obstruction of a medical officer of health. The man was arrested on Saturday after making a video of himself coughing and sneezing over fellow shoppers at the Christchurch's Fresh Choice supermarket in Barrington.

In the video, posted to Facebook, the man appears to smile as he coughs repeatedly on others. He then turns the camera on the shoppers as he apologises.

On Sunday, the Health Director General Ashley Bloomfield announced 89 new cases around the country, bringing the total number of confirmed or probable cases to over 1000.

There were 48 new confirmed cases and 41 probable cases, bringing the total to 1039. Of those, 156 had fully recovered. On average there have been 2448 tests per day with 3093 tests completed yesterday. In total there have been 36,209 tests.

The death toll for coronavirus in New Zealand remains at one.

There are 13 people hospitalised with the disease, including three in intensive care - one in Wellington and two in Auckland.