An epidemiologist says an impending move to home quarantine for people with Covid-19 involves huge risks, but there isn't much other option.
The Government says isolation at home for "low risk" Covid-positive people may be permitted within a week.
Rod Jackson told Morning Report it suggests the government believes the spread of Covid-19 is much wider than had been thought.
"Last night, there were 75 unlinked cases in Auckland. What that means is there's a lot more cases out there.
With Delta, it just spreads so quickly, so widely that, you know that that's the big concern. It's what makes a Delta outbreak so much worse than any of the previous ones. It's just the speed of the spread, and that just overwhelms all services.
"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."
He said a move to alert level 4 may not stop the growth in cases, because rule breakers are the ones who are spreading the virus.
"You can be really hard on them [rule breakers], but you're probably not going to ever stop them.
"We have to make sure that our cars' brakes work, we need to make sure that we're doing everything and we're following all the rules because the more we do that, the more we can slow it down."
He said it's important as many people as possible get vaccinated, and it should be mandatory in more areas.
"I think we need to take our mandatory vaccination rules much further. 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 I think the government needs to say okay."