Rest homes will be reminded about the importance of maintaining the strictest standards to prevent the spread of Covid-19, after the second death linked to a facility in Christchurch.
New Zealand now has four fatalities - two of them were linked to Rosewood rest home, which still has about 30 cases.
The Director of Public Health, Caroline McElnay, said that was a high risk cluster and there could be more serious illness or even death.
She backed the decision of the Canterbury District Health Board to move the group of 20 residents from Rosewood to Burwood Hospital, two of whom were now among the fatalities.
"These are a group of frail individuals who needed ongoing support; they were moved as a group but kept in isolation."
Experience here and overseas showed the impact this virus had on a very "frail and vulnerable group", Dr McElnay said.
"I have been assured today that all the residents moved to Burwood whilst they're frail and not well, they're being managed and given the best possible care," she said.
"But we want to acknowledge that Covid-19 for this age group and people with significant underlying conditions can be a very unpleasant illness and sadly we do know people can die from it."
Aged care facilities were "very mindful of the risks" to their residents, she said.
But they would be directly reminded by health authorities about the need to take extra care: the need for visitor restrictions, staff staying home if they are sick, using personal protective equipment where available and appropriate, and having good infection controls in place.
Dr McElnay said there were no specific concerns from health authorities about how rest homes were operating but it was helpful to reinforce the message.
Investigations about how Covid-19 got into Rosewood in the first place were ongoing, she said, including through further testing.
There are now three clusters associated with aged care facilities - another one in Christchurch and one in Waikato.
The second Christchurch cluster was the George Manning rest home with 14 cases among both staff and residents. It was "well contained" and not likely to increase, Dr McElnay said.
She sympathised with concerns many families would have during lockdown, being unable to go and see loved ones personally.
Anyone worried about family in an aged care facility is asked to contact their local District Health Board.
Residents moved for bigger facility, not admission to hospital - DHB
A group of Rosewood rest home residents who were moved to Burwood Hospital earlier in the week were not shifted there because they needed to be admitted to hospital, the Canterbury District Health Board says.
Canterbury DHB Emergency Coordination Centre incident controller Sue Nightingale said the residents were moved to Burwood because the needed to be in a bigger facility where they could be safely isolated and cared for.
The ward they were in at Burwood had large rooms with ensuites and there were dedicated spaces for staff to put on and take off their personal protective equipment (PPE), Nightingale said.
"It is however important to understand that some of these residents have underlying health concerns and were unwell before they arrived at Burwood," she said.
"The care they are receiving is consistent with the psychogeriatric care they would have been provided in an aged care facility and includes, where appropriate, end of life/palliative care."
Nighingale said the lack of appropriate staffing and limitations around isolation were significant constraints at the Rosewood facility.
"Relocating these vulnerable residents to Burwood was a necessary and important to provide the space and facilities needed to provide quality care," she said.
- If you have symptoms of the coronavirus, call the NZ Covid-19 Healthline on 0800 358 5453 (+64 9 358 5453 for international SIMs) or call your GP - don't show up at a medical centre
Read more about the Covid-19 coronavirus:
- See all RNZ Covid-19 news
- Your Covid-19 questions answered - from health and jobs to keeping anxiety in check
- A timeline: How the coronavirus started, spread and stalled life in New Zealand
- Covid-19 symptoms: What they are and how they make you feel
- Touching your Face: Why do we do it and how to stop
- Scientific hand-washing advice to avoid infection
- Coronavirus: A glossary of terms
- The Coronavirus Podcast