There are 29 new cases of COVID-19 in New Zealand, Director-General of Health Dr Ashley Bloomfield has confirmed.

That's made up of 23 confirmed cases and six probable cases. There are no new deaths, but 14 people are in hospital. Four are in ICU.

New Zealand has 1239 cases overall. With an increase of 35 on Wednesday, 317 people have recovered. That increase is higher than the number of new cases reported on Thursday.

Prime Minister Jacinda Ardern said what New Zealanders have done over the last two weeks with the lockdown is "huge". Aotearoa has been under the restrictions for the last two weeks in an effort to limit person-to-person contact, and therefore exposure to the virus.

Ardern said on the eve of the lockdown, modelling showed New Zealand was on a similar trajectory to Italy or Spain, with over 10,000 cases expected by now if no actions were implemented. New modelling shows the current controls have had a significant impact.

"You are breaking the chain of transmission and you did it for each other," she said. "You have saved lives".

There continues to be a strong link to overseas travel (41 percent), 44 percent are contacts of cases in New Zealand. Two percent are community transmission. The rest are under investigation.

The three largest clusters are linked to the Matamata bar (64), the Bluff wedding (87) and Marist College (84).

In terms of testing, Dr Bloomfield says there were 3990 tests processed on Wednesday. The daily average over the last week is 3547. 

Ardern said early work was underway on a phone application to help with contact tracing.

If New Zealand continues to see numbers drop and no community transmission is detected, it is likely we will have Alert Level 4 lockdown restrictions lifted in two weeks.

A decision on when the lockdown will end will be made on April 20, two days before it is scheduled to end. Ardern warned if we move too early we "will go backwards".

However, authorities are advising people not to become complacent, especially over the long Easter weekend. Police have sent several warnings to the public not to head away over the weekend, with checkpoints being set up along a number of roads.

Even if New Zealand does leave lockdown in two weeks, it is likely some restrictions will stay in place. For example, if we go down to Alert Level 3, "affected educational facilities" will remain closed, mass gatherings are banned, public venues are shut and "alternative ways of working [are] required". The Minister of Education said on Thursday that parents should not expect to be sending their children back to school as soon as the lockdown is finished.

Several international papers have warned that if countries reduce intensive measures after believing they have contained or eliminated the disease, if a spike occurs, those restrictions will need to be ramped up again extremely quickly. That may mean a country goes in and out of lockdown multiple times until a vaccine is developed.

Border restrictions may also stay in place for a long period of time while other countries attempt to stamp out the virus. Mandatory quarantining was announced by the Prime Minister on Thursday.

Worldwide, there are 1.5 million COVID-19 cases, with 88,000 having died of the illness.

How can I protect myself? 

• avoid touching the mouth, nose and eyes with unwashed hands
• washing your hands before eating
• carrying a hand sanitiser at all times
• carry tissues at all times to cover the mouth and nose when coughing or sneezing (then dispose of it)
• avoiding shaking hands, kissing cheeks
• regularly cleaning and sanitise commonly used surfaces and items, such as phones and keys
• avoiding close contact with people suffering from or showing symptoms of acute respiratory infection
• seeking medical attention if you feel unwell.