New Zealanders will need to wear masks and get tested "the minute they have any symptom" of Covid-19 for the country to control the latest cluster under lower alert levels, Dr Siouxsie Wiles says.
Prime Minister Jacinda Ardern said if everyone played their role, the Covid-19 cases can be managed in 'level 2.5'.
Auckland University microbiologist Dr Siouxsie Wiles said she is worried that it's not yet clear how well the Auckland cluster is contained.
"I would have preferred that we stay at level 3 for just a little longer because I feel that might have helped us get back to a level 1 much more quickly.
"But I understand that businesses are hurting and everyone wants to get us moving around more."
The question was how long it will take to get the cluster under control now that Aucklanders were moving around much more, she said.
"Now we're all moving around there is the opportunity if there are people who are infectious and don't know it yet that they could spread it somewhere else."
An option would have been to open up Auckland more, but to make sure people in the region were not travelling, she said.
Wiles said it could be "a couple of weeks" before it's clear whether the Auckland cluster is under control.
"Hopefully it will be sooner than that.
"The really important thing is that everyone around the country is really, really on it in terms of keeping a lookout for symptoms, going and getting tested the minute they have any symptom they think could be Covid -19.
"Every day you delay getting tested is a day longer than the contact tracers have to try and trace back to see who you could have infected.
The more people wear masks in confined spaces the better it will be, she said.
"If you're having meetings in offices, that sort of thing, everyone should be wearing a mask."
Wiles said the contact tracing system is very different to the one in the first lockdown, and the question will be if it can stay ahead and ring fence any cases.
'We need a very vigorous 2.5 to stamp out this outbreak'
Otago University epidemiologist Professor Michael Baker said moving to alert level 2.5 was the right call.
"Unfortunately we're still seeing a moderate number of cases every day and that reflects conditions applied around 10 days ago when these cases occurred. It suggests that at level 3, and with all the extra testing and contact tracing, we have bought this outbreak under control."
However, he said if we had moved to level 2 it would not be enough to control the outbreak.
"I think we really need a very vigorous 2.5 to stamp out this outbreak, or give us a good chance of stamping it out."
Baker said whether the virus is brought under control is in the hands of Aucklanders abiding by the rules, and getting tested and staying at home when they have cold or flu symptoms.
The country has moved to a more nuanced approach, with more contact tracing and testing where we don't necessarily need to be in a severe lockdown for seven weeks to eliminate the virus.
"That's good, that means less disruption and less time with lockdown or staying at home, but it does depend on people really following these rules.
"I think we all know what we have to do, and the big addition is face masks. There's a lot of evidence internationally that, if people really embrace that, it does actually stamp out the virus quite effectively.
"This is really in all of our collective hands now. Unlike being in a lockdown, which is very simple, anything below level 3 depends on the behaviour of everyone and particularly people in Auckland at the moment."
Royal College of GPs medical director Dr Bryan Betty backs the decision for a 'level 2.5' in Auckland rather than stepping down to level 2.
"We know that as you jump down the levels there is an increased risk of transmission occurring. I think we'll have to wait for the next week or two to see what happens in terms of community transmission. Our hope, like the rest of New Zealand is that the transmission is contained," he told Morning Report.
"There is an argument to say we could have gone a bit longer at level 3 from a health perspective, but we'll wait and see."