There were 9047 new community cases of Covid-19 on Thursday, and the Ministry of Health revealed 13 more Covid-related deaths.
Video / Dean Purcell / Mark Mitchell / Michael Craig
A Covid-19 expert does not expect case numbers to dip below 5000 but to instead increase in the coming months.
Experts said the point when community case numbers would tick up depended on four to five factors, including human behaviour.
The Ministry of Health reported 9047 community cases yesterday, a further 13 Covid-19 related deaths and 484 hospitalisations, including 15 in intensive care.
The University of Auckland senior lecturer and principal investigator at Te Pūnaha Matatini Dr Dion O'Neale said a baseline of 5000-6000 Covid-19 cases was expected for some time.
"They are not going to drop below that, the next thing we will see is that they go up."
O'Neale said there were three factors that would drive the arrival of the second wave in cases.
They were a change in people's behaviour, perhaps since the change in the traffic light setting; seasonal effects and the increase in respiratory illnesses over winter; and the reinfection of people who previously had the virus, paired with waning immunity from vaccinations and boosters.
"If you say behaviour change is driving it, then we could expect to see numbers ticking up basically any time from now onwards.
"In a month or so we would see a decent size in that hump of case numbers going up. If people remain cautious and it's only reinfection that is driving things, then it may be August until you start to see those numbers going up ... and everything in between."
Dr Dion O'Neale is an applied mathematician at Te Pūnaha Matatini and a senior lecturer at the University of Auckland. Photo / Supplied
Along with these factors, University of Auckland epidemiologist Professor Michael Baker said the evolution of the virus to become more transmissible or better at evading immunity would also influence case numbers.
"A plateau, a perfect equilibrium, would be very unlikely, given we've got the different forces pushing the equilibrium in different directions.
"Given, over time, the factors favouring the virus are going to increase as we move over the next few months, we'd certainly expect numbers to go up."
He said another wave of cases would probably be manageable.
"One possibility is quite a long, slow gentle wave starting in Auckland and it's gradually going to merge with the rest of the country where we'd expect cases and numbers to track up, gradually over the next couple of months, and then perhaps descend again.
"I think it's really unpredictable because the factors I described are quite poorly qualified in New Zealand."
Yesterday, there were community cases reported in Northland (276), Auckland (2519), Waikato (550), Bay of Plenty (335), Lakes (129), Hawke's Bay (281), MidCentral (344), Whanganui (108), Taranaki (215), Tairāwhiti (137), Wairarapa (95), Capital and Coast (589), Hutt Valley (236), Nelson Marlborough (358), Canterbury (1505), South Canterbury (185), Southern (1065) and the West Coast (113).
The location of seven cases was unknown, the ministry said in a statement at 1pm.
There were also 80 Covid-19 cases detected at the border.
The ministry noted the seven-day rolling average of cases yesterday - 7705 - was similar to last Thursday's average of 7935, which was a reminder to stay "vigilant".
"Please continue to follow public health advice to stay at home, away from school or work if you're feeling unwell."
Thirteen Covid-related deaths were reported by health authorities yesterday, which took the total number of people who had died with the virus to 723.
The deaths reported yesterday were for people who have died over the previous nine days, apart from two deaths on April 4.
The seven-day rolling average of reported deaths is 13.
The ministry said two of the people whose deaths were reported yesterday were from Auckland, three were from Bay of Plenty, two were from Waikato, one was from Taranaki, one was from MidCentral, one was from Hawke's Bay and three people were from Canterbury.
Two were in their 50s, two in their 60s, one in their 70s, three in their 80s, and five were over 90.
There were 484 cases in hospitals across the country yesterday.
They are in Northland (36), Waitematā (74), Counties Manukau (60), Auckland (105), Waikato (33), Bay of Plenty (14), Lakes (three), Tairāwhiti (one), Hawke's Bay (12), Taranaki (seven), Whanganui (three), MidCentral: 7; Wairarapa (seven), Hutt Valley (14), Capital and Coast (nine), Nelson Marlborough (six), Canterbury (60), South Canterbury (four), West Coast (one) and the Southern region (33).
University of Canterbury epidemiologist and Te Pūnaha Matatini Covid-19 modeller professor Michael Plank said case numbers among some older age groups were at the same level as their past peaks.
"We've definitely seen a shift towards the older age groups ...That's going to potentially keep hospitalisations and deaths high because those older age groups are much higher risk."
More younger people had been infected with Covid-19 earlier in the outbreak while infection rates had been lower in older age groups, he said.
