The plan for people with Covid-19 to isolate at home suggests the government believes the spread is wider than had been thought, epidemiologist Rod Jackson says.
Covid-19 Response Minister Chris Hipkins said home quarantine would be introduced "fairly soon" as a necessary step to prevent MIQ spaces being limited even further for people coming to New Zealand from overseas.
University of Auckland professor of epidemiology Rod Jackson said the outbreak had to be slowed down.
"Last night, there were 75 unlinked cases in Auckland. What that means is there's a lot more cases out there."
He said the speed of the spread of Delta variant makes this outbreak worse than any previous one.
"I think the government's clearly signalling that MIQ is going to be overwhelmed, the next thing is hospitals are going to be overwhelmed, everything's going to be overwhelmed.
"We've just got to got to slow it down as much as we can."
There were "huge risks" involved with home isolation, he said, "but to me, it suggests that ... they believe this problem is much much wider than we thought".
"We are in a race against time to get everyone vaccinated, we just have to use everything in our power to slow [the outbreak] down as much as possible."
Jackson said vaccination should be mandatory for more sectors.
"I think it has to be the police, it has to be supermarkets. The other thing is that businesses are crying out for the license to introduce their own mandates."
With more than 80 percent of eligible New Zealanders having had at least one vaccine dose he said "the tide was turning" against those who were not vaccinated.
Jackson said he had supported the move to level 3 for Auckland last month, and believed returning to a period of level 4 lockdown may have little effect on the growth of cases.
"Covid is spreading among a group of people who are breaking the rules.
"You can be really hard on them, but you're probably not going to ever stop them."
University of Auckland public health associate professor Dr Collin Tukuitonga is sceptical level 3 had made little difference to the outbreak.
"That's a very narrow view," he said.
"The people who don't obey the rules is only a subset of the total number of people who are likely to move around and spread the virus.
"Yes, these are people that are at most risk of spreading it but if you permit people to move around more than we did before you will no doubt transmit the virus around.
"I can't see how you can say that level 3 and level 4 are the same risk."
The drop to level 3 was premature and very risky for Māori and Pasifika where vaccination rates remain low, he said.
"I was on the record as saying tired Aucklanders and business people got the louder voice this time, and those of us in public health had a quieter voice."
The government should be prepared to go back to level 4 if things got really tough, he said.
Home quarantine 'not for everyone'
Tukuitonga told Morning Report isolating at home would not be suitable for those living in crowded multigenerational households.
"It's not for everyone," he said.
"You've got to be quite clear about the criteria, you got to have a group of people you can trust to do the right thing, you need to make sure they have a good understanding of the risks, the facilities at home have got to be up to scratch.
"It can't be a small state house with three bedrooms and 12 people."
Tukuitonga says anyone isolating at home must understand the risks involved, can be relied on to follow the rules, and have a suitable home.
He said some may think the move is risky, but it's going to have to happen with cases growing.
"I know some of my public health colleagues will say 'absolutely not, this is a highly, highly risky measure', but as I say, you've got to be pragmatic.
"When we run out of facilities we've got to look at different options."