A top epidemiologist believes self-isolating and testing will be the "weakest part" of the Government reopening plan. 

New Zealand's international border will reopen in five stages from February 28. MIQ will be removed for most travellers, replaced by self-isolation and Covid-19 tests on arrival. 

But as a highly infectious variant continues to spread across the world, Otago University epidemiologist Professor Michael Baker said self-isolation is a "big step down". 

"We don't want to be further driving our Omicron outbreaks in New Zealand by importing cases, so it [self-isolation] could be tightened up in many ways." 

While the focus with Omicron has shifted away from elimination Baker said it is now about "slowing the spread" which can be reflected in the border settings. 

Michael Baker said he has questions about how it will work once New Zealanders return in large numbers. Photo / Supplied 

However, health officials have said household members can go about their normal routine while a returnee is isolating at their house. 

"While in isolation, the household members that the person has not travelled with can come and go as normal unless the traveller returns a positive test," a Ministry of Health spokesperson said. 

Baker said he has questions about how it will work once New Zealanders return in their thousands. 

"We are reducing the control over isolation and we are reducing the testing to detect infected people, so it's a hugely scaled-down border control measure." 

Earlier today Prime Minister Jacinda Ardern said the move to self-isolation had a level of personal responsibility. There were potential fines for breaches of between $4000 and $12,000. 

While there is a chance of some returnees with Covid-19 being out in the community during their self-isolation time, in the context of high community case numbers, Baker said it may be a "small contribution". 

But he said it is hard to predict whether that will be important or not. 

"By the times these measures come in we would be expected to see high rates of transmission in the community. 

MIQ will be removed for most travellers, replaced by self-isolation and Covid-19 tests on arrival. Photo / Dean Purcell 

"So, I think the central rationale is sound at this stage in advance you would want to be making sure that it is trying to achieve what it is meant to do." 

Baker hopes there will be an option for those who may be isolating in a vulnerable household to stay at MIQ to ensure the safety of those in the household. 

"There will be widespread transmission but we are at the same time wanting to slow it down, which is what this strategy is about - but also not expose vulnerable people to infection risks." 

Speaking on the newly announced testing plan, Baker said he would still like to see the use of PCR tests on arrival, to understand how many cases will be entering the country. 

"One of the questions I have is whether we would consider having a routinely PCR test and not a rapid antigen test for those coming in for at least a period, so it can give us information on whether the variant coming in will be changing at all." 

All arrivals will be given three rapid antigen tests upon arrival at the airport, to use at home. Photo / NZME 

All arrivals will be given three rapid antigen tests upon arrival at the airport, to take home. 

One for use on day 0/1, and one for use on day 5/6, with one extra for backup. 

"That gives us the best chance of identifying cases that have come across the border," Ardern said. 

"If a positive result is returned at any point, returnees will be asked to get a follow-up PCR test at a community testing station." 

More guidance for returnees' self-isolation requirements will be made available on the ministry's website by mid-February. 

- by Zoe Holland, NZ Herald