Epidemiologist professor Michael Baker says the Government should consider putting southern Africa on its very high risk travel list, after the discovery of a new variant of Covid-19.
The World Health Organisation has named the B.1.1.529 Covid variant "Omicron" and an advisory group has said it should be designated as "of concern".
In a statement, the WHO said preliminary evidence suggests the latest variant carries a "higher risk of re-infection than other variants of concern".
The Ministry of Health said this afternoon officials were assessing the latest international information on Omicron.
"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."
So far, the ministry understands there have 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."
"We will advise on any potential impacts for New Zealand, noting that we remain in a good position to minimise the impact of any new variants with isolation and routine testing of international arrivals."
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.
New Zealand's "very high risk" list means travel from those countries 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.
Baker told the Herald the Government should consider adding southern Africa to the list to turn up its Covid-19 response if needed.
"I'm sure the actual number of travellers to New Zealand from those countries is probably tiny.
"I think it would probably be relatively easy to put those countries in the same grouping as Papua New Guinea (already on the list) as the highest risk and that does give you extra precautions."
Baker said he understood the new variant was worrying for people.
"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."
Baker also noted New Zealand was among a minority of countries which still managed their borders tightly, with layers of protection like pre-travel testing and quarantine.
"It means we're in a completely different situation compared to the rest of the world. We can keep this virus out if we need to."
A spokesperson for Covid-19 Response Minister Chris Hipkins said they were monitoring the situation.
The Ministry of Health has been approached for comment.
Meanwhile, Deputy Prime Minister Grant Robertson won't rule out resorting to future lockdowns.
He told Newshub Nation the alert level system would sit in the background of the new traffic light system.
It was not something the Government was considering at the moment and if lockdowns had to be used, they would be a last resort, Robertson said.
"But we said from the beginning of the launch of the framework in late October that we have to be mindful of the fact that Covid is not finished around the world. We will keep an eye on any new variants.
"There is no proposal to return to lockdowns, but we do have the alert level framework sitting in the background if it needed to be used."