New Zealand has reached a new low for coronavirus cases under lockdown, and recorded no further deaths after three were reported over the Easter weekend.

Director-General of health Dr Ashley Bloomfield, at a Sunday press conference, said the fewer new cases were encouraging, but warned there may still be more deaths from a group of rest home residents afflicted by Covid-19.

There were 18 cases of coronavirus to report from Saturday, a number fewer than any daily total since March 22, three weeks ago. Of these, 14 tested positive for the virus and 4 were probable cases.

JOHN KIRK-ANDERSON/STUFF Residents of the Rosewood rest home who have coronavirus have been moved to Burwood Hospital in Christchurch.

"New Zealanders should take heart in that, our efforts are paying dividends," Bloomfield said.

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New Zealand now had 1330 cases total. More people recovered from the virus then were confirmed as having it, the 49 recoveries bringing the total to survive it to 471.

HAGEN HOPKINS/STUFF Director-General of Health Dr Ashley Bloomfield gives a coronavirus update.

There were 14 people in hospitals around the country, and five people in intensive care beds. One was in a critical condition.

Bloomfield said the residents of Rosewood Rest Home who contracted the virus would continue to have their care managed at Burwood Hospital, but would not be included in the tally of hospitalisations.

Two elderly patients from this virus cluster have died in recent days, a woman in her 90s and a man in his 70s.

"We may well see further deaths over the coming days, I'll just be honest with you about that," Bloomfield said about the Rosewood residents.

The significant clusters of the virus at aged-care facilities, two in Christchurch and one in Waikato, was a concern.

Bloomfield said he had written to all of the district health boards asking that staff "systematically" inspect each aged-care facility, to assess their protocols to prevent spreading infection and the amount of protective equipment in stock.

"We want to be really sure the settings are water-tight to be able to protect staff and residents .. What we have found with the clusters that have broken out, there were some deficiencies in the actual procedures."

He could not provide an example of the deficiencies found.

Aged Care Association chief executive Simon Wallace had called for all rest home staff and new arrivals at rest homes to be tested, describing the two Rosewood deaths as a "tragedy waiting to happen".

Bloomfield said he would not direct routine Covid-19 testing of rest home residents and staff, but testing was encouraged for symptomatic rest home residents, and new residents were required to be isolated for 14 days in case they have the virus.

Broader testing of asymptomatic residents at rest homes at the centre of virus clusters could occur, he said, but that was a decision for regional medical officers of health.

But he was encouraging more liberal use of Covid-19 testing in certain areas.

Bloomfield said he had sent text messages to the chief executive of the Whanganui DHB, asking that more testing be done as the region had a lower testing rate than others.

There might be more regions and groups that require greater testing. Bloomfield said he was yet to see advice from the ministry's epidemiological experts on this.

There were 2421 tests processed on Saturday, a reduction on previous days due to the quieter Easter weekend.

Bloomfield confirmed there were 13 New Zealanders returning from a cruise ship that docked in Uruguay and was afflicted by the virus. They would be tested for Covid-19 and placed into quarantine.