Empty corridors in one hotel, vaccine stockpiles and mutant variants loom large in new debates about how to defeat Covid-19.
Epidemiologist Dr Michael Baker said alert levels "desperately" needed revision due to new mutations and the fact New Zealand's four-tier system was almost a year old.
New Covid-19 varieties, including some believed to be more infectious than earlier strains, have emerged independently in Brazil, South Africa and the United Kingdom.
Baker said New Zealand's alert level system worked well when introduced but now needed revision, and an integrated national facemask policy could be considered.
He said a new alert system could have more than four tiers.
It was crucial, he said, that security measures for people leaving managed isolation and quarantine were enforceable but not draconian.
Baker said current regional rule variations, such as Auckland's public transport facemask mandate, could be confusing.
Auckland's Pullman Hotel is emptying out as the Government works to decommission it temporarily and determine how a guest was infected with a mutant strain.
One man called the Herald to say a relative about to leave the Pullman worried she was putting herself and others at risk by flying to Wellington to self-isolate.
Rules for the Pullman changed after a guest with a new South African strain left the hotel and visited more than two dozen Northland locations not knowing she had the virus.
Since Thursday, Pullman guests leaving managed isolation have been asked to get a day-5 post-departure test and stay home until returning a negative result for Covid-19.
Microbiologist Dr Siouxsie Wiles said Pullman guests flying to other cities for self-isolation were not posing a greater risk if mask-wearing on flights was adhered to.
The Ministry of Health has said guests leaving the hotel for their five days of self-isolation can wear a mask while using public transport to get home.
Wiles said airlines should not serve food and drink on domestic flights, as doing so undermined efforts to encourage mask-wearing.
She said the short duration of domestic flights made it feasible to not serve food and drinks in-flight.
The Pullman will soon be devoid of guests but other hotels in the system are full. Not one vacancy before May 31 was listed on the official MIQ website on Monday.
Meanwhile, the roll-out of vaccines has given hope to some wealthy countries in recent weeks.
But the World Heath Organisation has voiced concern about wealthy countries securing vaccine stocks while some poorer nations struggle to vaccines.
"It's not acceptable that the 'Global South' is going to have to wait another year or two," Wiles said on Monday.
Apart from possible ethical issues, it was impractical for wealthy countries to allow poorer ones to fall behind in vaccinations, she said.
Wiles said countries such as New Zealand, Australia and Taiwan - which achieved elimination - could be at risk if huge outbreaks involving new strains emerged elsewhere.
Last week, an International Chamber of Commerce study found "vaccine nationalism" could cost the global economy up to $12.8 trillion dollars.
That enormous cost, many times higher than the price of supplying poor countries with vaccines, derived from projected shocks to global trade and economic production.
"The more open an economy is, the stronger the economic incentive it should have in ensuring trading partners have access to vaccines," the study added.
Wiles said hoarding was not necessarily a funding or foreign aid issue, but related to vaccine supply.
She said India and South Africa had asked the World Trade Organisation to temporarily suspend intellectual property rights so poorer countries could access Covid vaccines.
But some wealthy countries rejected that, saying IP systems were needed to incentivise new inventions of vaccines and treatments.
Wiles said procedures effective at keeping earlier Covid strains out might not be resilient enough for more transmissible new varieties.
No new Covid-19 cases were reported on Monday and New Zealand had 69 active cases.
By Monday afternoon, more than 97 per cent of people who'd left managed isolation at the Pullman between January 9 and 24 had tested negative.
The Ministry of Health said it was waiting for results from five other Pullman guests.