One of New Zealand's top experts in COVID-19 says our alert level system is "really out of date" and "not fit for purpose anymore".
Since its introduction in March 2020, the alert level system has had four levels - but Michael Baker, professor of public health at the University of Otago, says it's too "crude" because Kiwis treat it as though it only has two.
"We've got a system where level 2 doesn't really mean very much for people," he told Newshub.
"Most people don't do things very differently [than at level 1]. You've more or less got two settings in New Zealand, which is some basic concern at level 2, then lockdown. We've got a very crude system."
It took just four days from its introduction for New Zealand to move from level 2 to level 4. The entire country has now been at level 1 for five months, with no untraced community transmission of the virus.
But - as NIkki Turner, director of the Immunisation Advisory Centre told The AM Show on Wednesday, the highly contagious Delta variant of the virus is "only a plane flight away".
A short plane flight too - Sydney posting its biggest numbers of the current outbreak so far on Thursday, recording 239 new infections. Dozens of them were infectious while in the community.
"We are still vulnerable because people with the Delta variant are arriving every day and going into MIQ," said Dr Baker. "We're also seeing situations at our sea ports with infected shipping and fishing crews arriving here. We are connected with the outside world... and that always means vulnerability to reintroducing the virus."
While there have been tweaks to the alert level system - such as Auckland's 'level 2.5' in the August outbreak - Dr Baker says what the four-level system lacks is clear in-between steps, particularly around mask use and use of the COVID Tracer app.
While New South Wales has struggled, he says other states managed to control their outbreaks by adopting a New Zealand-style "rapid, vigorous" response - Victoria combined mass-masking with mandatory signing-in to high-risk locations.
The latter is "really essential for giving you a head-start for contact tracing", said Dr Baker, noting it's still optional in New Zealand.
As for masks, Dr Baker said including a level which required their use in public would help. In Victoria at present, they "must be worn both indoors and outdoors when you leave the house unless an exception applies".
When New Zealand's alert level system was devised, it was still generally believed the virus was spread via droplets - and while mask use was encouraged, it wasn't mandated at any level. Only later did scientists prove the virus was airborne, and that masks greatly minimised the number of virus particles an infected person would spread.
"If you want to avoid a lockdown and… go back to work and school and resume some of your normal activities, they just require masking across whole populations because that's a very good way of stopping the spread of this respiratory virus, which is transmitted as an aerosol in indoor environments," said Dr Baker.
"New Zealand has not developed a systematic approach to mask use. We're still not experienced with masks, we don't know when to wear them. Our alert level system is really out of date, not fit for purpose anymore. It doesn't take into account how this virus is transmitted.
"So it means if we start to see the beginning of a Delta variant outbreak or we're concerned the risk level is rising, we're just going to have to go straight to quite an intense lockdown - we just don't have the intermediate levels and good use of mass-masking."
Dr Baker and others have previously called for a seven-level alert system - from 0 to 6 - with masks mandated in some locations from level 2. COVID-19 Response Minister Chris Hipkins said at the time the present system allowed for "nuanced changes as required".