It has now been 100 days since the last case of community transmission of Covid-19 in New Zealand.

The Ministry of Health said today that there were no new cases of Covid-19 to report.

It is the fourth straight day of no new daily cases.

Director general of health Ashley Bloomfield thanked every person who had been tested.

"Achieving 100 days without community transmission is a significant milestone," he said in a statement.

But he warned against complacency, echoing a sentiment expressed this morning by Prime Minister Jacinda Ardern.

"We have seen overseas how quickly the virus can re-emerge and spread in places where it was previously under control, and we need to be prepared to quickly stamp out any future cases in New Zealand."

There are 23 active cases, all contained in managed isolation facilities, while the number of New Zealand's confirmed cases remains at 1219.

Yesterday there were 4249 tests - 542 from people in managed isolation or quarantine facilities - bringing the total number of tests completed to date to 494,481.

The higher testing numbers per day have been supported by pop-up testing centres.

Ardern said earlier today that 100 days would be a milestone but it didn't minimise the risk in any way, given the ongoing pandemic around the world.

"We need to be vigilant."

She said there was a resurgence plan ready to roll out if there was a surge in cases in New Zealand.

Bloomfield repeated his advice for people to ask their GP or call Healthline if they have symptoms of Covid-19, and to stay at home if unwell.

"Keep a record of your movements so you can refer to them for contact tracing if required. Don't let the team down – none of us can afford to do that."

High testing numbers are crucial as they underpin confidence in whether there is any community transmission.

Taranaki, Auckland, Canterbury and Mid Central DHBs had pop-up testing stations yesterday.