New Zealand is on track to see 10,000 Covid-19 infections a day - with most cases to be recorded in Auckland - by mid-March, an expert predicts. 

The Ministry of Health reported 1573 community cases yesterday, with most in Auckland - 1140. 

The remaining cases were in Northland (31), Waikato (143), Bay of Plenty (29), Lakes (35), Hawke's Bay (2), MidCentral (3), Whanganui (11), Taranaki (8), Tairāwhiti (8), Wairarapa (30), Capital and Coast (20), Hutt Valley (22), Nelson Marlborough (49), Canterbury (7), and the Southern (35) region. 

University of Otago professor Michael Baker says the trend of increases in case numbers was exactly what was expected and indicated the outbreak could peak in March. 

"[It has been] three weeks since community transmission was really established in New Zealand and we saw that initial uptick in cases," Baker told the New Zealand Herald. 

"The moving average of cases has not deviated from a steeply rising exponential curve where numbers are doubling maybe every five days roughly, give or take a day or two. 

"If that trend continued from the current numbers, we could be hitting 10,000 cases a day by early March. 

"That's why we will need all of the tools we have available just to try and dampen that rise in cases. We may do a bit better than that if all New Zealanders really do their best to get their boosters, to get tested and isolate, and to limit transmission by using masks indoors and limiting their social gatherings." 

However, Baker said even if we did reach the 10,000 predicted cases, we may not actually see them due to a lack of testing capacity. 

"We will need to think about other tools, [such as] much higher availability of rapid antigen tests," Baker said. Certain locations such as hospitals could test people, as Middlemore is doing, as a way of detecting infections in the community. 

Auckland was about two to three weeks ahead of the rest of the country in terms of case numbers, Baker said. 

"It's going to mean that we will see at a national level a peak that actually includes peaking at different places at different times." 

New Zealand's positivity rate - the percentage of tests that are positive - was heading towards sitting consistently above 5 per cent, indicating there was widespread transmission, he said. 

"It is basically saying if you did more testing you would find more cases because testing is only picking up a minority of cases. It is a sign that there is now widespread transmission, particularly in Auckland, and it means that we will be missing quite a few cases." 

As well as the new record number of cases yesterday, 63 people - with an average age of 62 - were in hospital with Covid-19 but none was in intensive care. They are in hospitals in Auckland, Rotorua, Tauranga, Waikato, Wellington and Tairāwhiti. 

A Ministry of Health statement yesterday said that since January 22, when the first Omicron case was detected in the community, double-vaccinated cases have been 10 times less likely to require hospitalisation than unvaccinated cases. 

"Four per cent of unvaccinated cases have required hospitalisation and 0.4 per cent of fully vaccinated cases have required hospitalisation." 

University of Canterbury associate professor of epidemiology Dr Arindam Basu said the present high case numbers were expected because epidemiologists had predicted them for a long time. 

"We have done well in the sense that we could've been far worse if there had not been the pick-up of the vaccination that we have experienced. 

"While it is true that numbers are high, it is also true that the numbers could've been far higher than what we have seen and the credit goes to generally sense prevailing in the community, that people got themselves the booster shots and things like that. 

"That helps to slow down what could have been a far more exponential spread. But the danger is not yet over. So I think it is a good idea to go now and get ourselves boosted." 

Meanwhile, thousands of people who work in district health boards have voted to strike after "15 months of fruitless negotiations all the while doing essential work during the pandemic", the Public Service Association (PSA) has announced. 

The group is made up of 10,000 allied, public health, scientific and technical professionals and the issues they are striking over include low wages and pay equity. 

PSA organiser Will Matthews said the depth of feeling from members and the support for industrial action nationwide is unprecedented. 

"There are over 70 groups of workers who will take strike action: from laboratory workers - who are responsible for the swift testing and return of Covid-19 tests and Covid-19 contact tracers - to sterile supplies technicians who clean and sterilise all surgical equipment prior to procedures - New Zealand needs each and every one of these professionals," Matthews said. 

"And yet many of them don't even earn a living wage." 

Yesterday testing sites continued to see high demand and the Ministry of Health asked people visiting the sites to be patient. 

In a 24-hour period to Thursday, 32,285 Covid tests were processed. 

It was important people only sought a test if they had cold or flu symptoms, have been identified as a close contact, or have been asked to get tested by a health official, the ministry said. 

"We understand that some people will be feeling worried or anxious at this time and will want a test for their own reassurance. 

"However, unnecessary testing will result in long waits at testing centres and could also delay results for those who urgently need them."