Community cases of Covid-19 continue to plateau in highly-vaccinated and still locked-down Auckland, with 127 new cases in the city yesterday, while another 20 cases were dotted around, mainly, the North Island.
The death toll also rose by one to 42 after a person aged in their 80s died in Auckland City Hospital, the Ministry of Health said.
The latest community case numbers - 145 in total around the country yesterday, including 13 in Waikato, four in Bay of Plenty and one in Canterbury - come as the world responds to fears of a new, more infectious variant.
Australia yesterday closed its borders immediately to nine African countries due to the variant, and brought in new quarantine requirements for Australians who'd recently been in them.
The World Health Organisation has named the B.1.1.529 Covid variant "Omicron" and an advisory group said it should be designated as "of concern".
Preliminary evidence suggests the latest variant carries a "higher risk of re-infection than other variants of concern", the organisation said in a statement.
One expert here said if vaccines were less effective against Omicron at preventing infection and transmission, the unvaccinated would likely be most affected, thanks to higher case numbers.
Of the 73 Covid-infected people in Auckland hospitals yesterday, 56 per cent were unvaccinated, 24 per cent partially vaccinated and 14 per cent fully vaccinated, with the vaccination status of the remainder unknown.
The vaccination status of three people in Waikato Hospital and one in Rotorua Hospital wasn't released yesterday.
Eight of those hospitalised are in intensive care.
Officials were assessing the latest international information on Omicron, the ministry said yesterday afternoon.
"This particular strain is in its infancy and as with any emerging developments to do with Covid-19 we are closely watching and monitoring evidence and countries' responses."
They understood there'd been 82 confirmed cases of the strain recorded in three different countries, although the case numbers associated with Omicron in South Africa are likely to be much higher.
"Early evidence from South Africa suggests Omicron may be more transmissible, however, research is still in progress and increased transmissibility may still not be borne out by more data."
The ongoing emergence of new variants such as Omicron also highlighted the importance of continuing whole genome sequencing on every case which crosses the border, the ministry said.
There were good reasons to think vaccines would still be effective against the new variant in preventing serious disease and death, University of Auckland senior lecturer Dr David Welch said.
"There are various ways of measuring vaccine effectiveness - the primary measure is whether it prevents serious disease and death", said Welch, of the Centre for Computational Evolution and School of Computer Science.
"Other measures of vaccine effectiveness are whether it stops people getting infected or whether it stops people transmitting the virus to others when infected.
"There are signs in Omicron's collection of mutations that vaccines may be less effective at preventing infection. Whether onward spread is also more likely at that point remains to be seen."
If vaccines were less effective against the variant at preventing infection and transmission, the unvaccinated would likely be those most affected, as case numbers would be higher, he said.
"Everyone will have a higher chance of being exposed to the virus. Getting vaccinated remains the best defence any individual can take against the virus."
The Government should consider putting southern Africa on its "very high risk" travel list, Professor Michael Baker said.
However, while the new variant was worrying for people, it was important not to catastrophise the situation, the University of Otago epidemiologist said.
"The best-laid plans can get upset by what the virus does. I hope it won't be the case.
"If this turns out to be a real threat to the effectiveness of vaccines, which is the main worry, then this might mean we have to review our plans for January and February next year on relying on home isolation entirely.
"But look, that's really leaping ahead, it's important not to catastrophise and we need to wait for more information."
New Zealand was among a minority of countries which still managed their borders tightly, with layers of protection like pre-travel testing and quarantine, which put us in a different situation to the rest of the world, Baker said.
"We can keep this virus out if we need to."
Travel from "very high-risk" listed countries - from December this will only be Papua New Guinea - is temporarily restricted to citizens, their partners and children, and parents of children who are citizens.
Other travellers, including New Zealand residents, can enter only if they spend 14 days outside a very high-risk country before their arrival here.
Meanwhile, of community cases reported yesterday, 85 are yet to be epidemiologically linked, including all 13 of Waikato's new cases, reported in Te Kūiti, Huntly, Hamilton, Te Kauwhata and Ōtorohanga.
Bay of Plenty's four new cases - in Kawerau, Te Puke and Tauranga - are all linked to previously confirmed cases, as are new infections in two people already isolating in Ruakaka, Northland yesterday.
The Ruakaka pair weren't included in yesterday's case numbers but will be in today's.
Officials are asking anyone in Northland, Auckland, Waikato and Bay of Plenty with symptoms – no matter how mild – to get tested, even if vaccinated.
The Canterbury case was first announced on Friday, but included in yesterday's numbers.
There were 5679 first dose vaccinations yesterday, and 12,222 second dose.
Nationally, 84.8 per cent of over 12s have received two doses, with 80 per cent of Pacific people and 67 per cent of Māori fully vaccinated.