Border restrictions are still needed, and MIQ will remain valuable even if Omicron is spreading widely in the community, epidemiologist Michael Baker says.
The ACT Party on Friday called for New Zealand to relax border restrictions, its leader David Seymour urging the government to "end its effective ban on travel to New Zealand", based on advice from the World Health Organisation (WHO).
The WHO statement advised against implementing blanket travel bans, saying they were not effective in suppressing international spread of Omicron and discouraged rapid reporting of new variants.
Seymour would not go so far as to say borders should open immediately - rather that the government should make clear that they would not be useful once Omicron was spreading widely within New Zealand.
"ACT believes that we should allow people to self-isolate. That may bring forward the release of Omicron into the community but equally it may escape MIQ, in fact it may have already," Seymour said.
"Once we get to a stage where you're just as likely to catch it from someone at Countdown as you are from someone off a plane it won't make sense to have isolation for non-infected travellers at all.
"When will the New Zealand government point out the obvious, that when Omicron is widely circulating within our borders we will no longer get a benefit from holding citizens outside their own country or putting them through the torture of MIQ?"
He said people like Professor Michael Baker from the University of Otago were correct to say closing the border could buy time, but it was now "far too late" for that.
Baker said the WHO had made similar statements before with sound reasoning, but MIQ and border restrictions had proven very valuable in the past.
"The restrictions on movement are often used by countries for their own ends, sometimes to exclude movement of people unnecessarily, and also even ... as a weapon for international diplomacy. But for outbreak control and pandemic control, managing borders has been incredibly effective," he said.
"In the Asia Pacific region this approach of managing borders has worked extremely well and particularly in the first year of the pandemic, when we didn't have effective vaccines, it saved millions of lives."
He acknowledged Omicron was changing the risk-benefit calculation, but maintained there was value in delaying its arrival as much as possible.
"With Omicron, which is highly infectious and also it causes less severe illness, the balance has shifted ... at the moment we're obviously trying to delay its arrival but when it starts circulating we're really moving to a mitigation approach.
"We have so many people arriving into New Zealand every day with Omicron, I mean the average has gotten up to 40 a day ... never had anything like that pressure, so a leak from MIQ or the airport or a seaport or an air crew is just very likely at this point.
"Once New Zealand is highly infected with Omicron and it's the same in countries around the globe, yeah you're going to relook at what the role of border management is, and MIQ."
Seymour appeared to agree with that kind of timeframe, with some provisos.
"We should allow people to enter New Zealand in a circumstance where community transmission is widespread in New Zealand. I don't think that we should try to bring it forward except we should be saying that doctors, nurses and other healthcare professionals should be able to skip MIQ now because we're going to need them tomorrow," Seymour said.
Prof Baker, however, maintained MIQ would remain a useful tool for New Zealand in future, for two reasons.
"One is that it's still a place where people who are active in the community can be looked after in a more supported environment without going to hospital ... the other, I think, even bigger reason ... we haven't seen the end of Covid-19 variants.
"We are going to get more surprises in the future, hence the need for maintaining our MIQ capacity at least for the foreseeable future. I think even a week seems to be a long way ahead for Covid-19 but ... regardless what happens with Omicron I think we're going to need this capacity."
He said greater access to high-quality masks like N95s, along with increased use of rapid antigen testing in some situations, could also help support New Zealand's health response if Omicron was spreading widely.