The Ministry of Health today reported 7487 cases of Covid-19, almost double yesterday’s infections, which experts believe could reach 10,000 by Christmas.

There were 3905 new cases yesterday, representing a 92 per cent increase between Monday and Tuesday infections. There were 40 virus-related deaths reported in the past week.

It is the largest percentage increase in case numbers between a Monday and Tuesday since the start of New Zealand’s Omicron outbreak at the beginning of the year.

Over a third of new cases today were in Auckland, where 2637 infections were reported, the highest number of cases in about four months.

Auckland University computer science senior lecturer Dr David Welch said this increase was not surprising given numbers had been “steadily” increasing over the last few weeks.

The seven-day rolling average of cases today is 5141. Last week it was 4042 and four weeks ago the rolling average was 2988.

Welch said, “If you look back at the graph, there was a plateau in mid-November and a noticeable rise in cases since then. It is a consistent pattern of doubling every three to four weeks at the moment.”

Infections reported on Tuesdays tended to be the highest numbers in any given week, he said.

Dr Samik Datta, of Covid-19 Modelling Aotearoa, told the Herald in October that cases were decreasing as the country came out from its second wave in July, but “since then, they have been increasing slowly, at a lower rate than the start of the previous two waves, with cases concentrated in older age groups.”

• Weekly numbers due as reinfections keep rising, latest wave keeps growing

Auckland University's Dr David Welch said an increasing number of Covid cases was being driven by several variants superseding variants which once dominated infections. Photo / Jed Bradley

Welch expected cases to peak at about 11,000 during the country’s third Covid wave. Projections from Covid-19 Modelling Aoteroa showed infection numbers could reach these numbers by Christmas, he said.

“If we are seeing cases double about every three weeks, we’re not very far away from the peak, it would happen before Christmas.”

Welch said the rise in cases now was being driven by a number of new variants which had a transmission advantage due to mutations on the virus’ spike protein. These variants had superseded older strains as people developed immunity from past infections or vaccinations.

Current cases were dominated by a collection of subvariants, including BQ 1.1 and BA 2.75, he said, where just a few weeks ago BA 5 was the dominant strain.

“[New cases] are mainly coming from reinfections, about half of cases are, and that’s the big thing at the moment,” Welch said.

Meanwhile, there were 398 people in hospital with the virus as of midnight last night, down 418 on Sunday.

Covid-19 antivirals like Pfizer’s Paxlovid pills have the potential to greatly slash the number of patients who get severely sick or die from the virus, but Auckland community and developmental paediatrician Dr Jin Russell said they were “ridiculously difficult” for people to access.

Anti-viral medications Paxlovid, Lagevrio and Veklury – which must be taken within the first five days of getting Covid-19 symptoms – were made free to about one million Kiwis in October.

In trial results reported earlier this year, it was found Paxlovid reduced the risk of hospital admission or dying from the virus by up to 86 per cent in non-hospitalised, high-risk adult and unvaccinated patients treated within five days of symptom onset.

Russell said there appeared to be multiple barriers to accessing antivirals. The Herald reported survey results from 1500 Kiwis which showed about 54 per cent of people knew little about the treatments.

Welch said while the country faced a “fairly” high prevalence of Covid-19 in the community it was important for people to remain vigilant about avoiding infection. Businesses hosting large events in particular needed to have measures in place to reduce transmission.

All main Covid-19 protections – the traffic light system, vaccine mandates and most mask requirements were dropped in September, which Welch said increased the importance people were aware of how they could stay safe.

“We know the environments Covid spreads in easily, those are crowded indoor environments. Businesses hosting large events need to remain cognisant of those measures; mask-wearing, testing, opening windows and monitoring CO2 levels.

“There are people who are still trying to avoid Covid and encouraging [these protection measures] are all effective. Businesses should work these into their usual safety plans,” he said.