A Covid-19 modeller says the case of someone attending gym classes before testing positive may prolong the time it takes to get on top of the Auckland cluster.
Professor Shaun Hendy told Morning Report that's because going to the gym is a high-risk activity.
"That's the type of activity where we might expect to see some spread."
At the gym you're indoors, breathing hard and close to other people, he said.
The Auckland Regional Public Health Service is asking anyone who attended three fitness classes at the Les Mills gym in Takapuna to stay at home and contact Healthline.
A spokesperson says these people are considered to be close contacts, and at greater risk of becoming unwell.
Hendy says he is confident in the ability of the contract tracers to find all of the gym members they need to.
But says this will prolong the time it will take to close the current Auckland cluster.
Les Mills' Takapuna gym has since been deep cleaned.
Spokesperson Brett Sutton says the gym is working with health authorities to contact trace others at the gym.
Extensive cleaning protocols were already in place and additional cleaning, including anti-viral fogging has been done, he said.
The person who tested positive also visited a supermarket but Hendy says this is of less concern because supermarkets are larger spaces where you're often not talking.
"Talking or singing or exhaling strongly, spreading the virus by aerosol, that's high risk.
"In a supermarket setting you're less likely to do that."
If we'd have stayed at level 3 for longer, it would have taken less time to get on top of the cluster, he said.
"There's a tradeoff. The longer you spend at higher alert levels, the shorter your time at the lower alert levels."
There hasn't yet been a chance to understand how effective this new level, 2.5, will be, he said.
"Our modelling shows that we could have this long period where we gradually get in to a few zeros, a few days with one case or so before eliminating.
"But there's also still the possibility that the cluster could kick off again. The modelling shows both scenarios are possible."
Hendy doesn't think restrictions should be eased today.
Auckland professor of Public Health Collin Tukuitonga agrees.
Tukuitonga told Morning Report typically a person was infected four to five days before becoming infectious.
Of the two new cases yesterday, one was a health worker at the Jet Park quarantine facility.
Hendy says even when wearing full PPE there's a risk you can contract the virus.
"That's why we suggested that there needed to be weekly testing of the workers at these facilities."
We should expect to see these types of cases from time to time, he said.
Tukuitonga understands that the team is still scoping who else has come in contact with the worker.
As for those working at quarantine facilities, like the worker who tested positive, he said there were guidelines for how they went about their work.
"There are no restrictions for how they live their life. There are infection control protocols they have to follow but I'm not aware of them being restricted."
Aged care facilities
Even if the government lowers the country's alert levels, aged care facilities will continue tightly managing visitors.
New Zealand Aged Care Association chief executive Simon Wallace said a return to unfettered access at its facilities will only happen when alert level zero is reached.
Until then, visits are by appointment only and limited in terms of numbers and duration.
"We're doing that on a risk-based precautionary approach simply because of the vulnerability of our population," he said.
It had been difficult for families but there was now a lot more more understanding about the vulnerability of aged care.