Microbiologist Siouxsie Wiles suspects the latest community case of Covid-19 could have been contracted via a surface in a cafe.
Dr Siouxsie Wiles Photo: Arvid Eriksson
Work is under way try to trace how a woman in her 20s, who lives and works in the CBD, caught the virus.
Some 100,000 Aucklanders who work in the CBD have been asked to work from home today.
Minister of Covid-19 Response Chris Hipkins said early results from genomic testing suggested a link to the Defence Force cluster identified a week ago.
Wiles told Nine to Noon the timing and location seemed to suggest a link with the Defence Force cluster and that finding the source would help stop further spread.
"One of the Defence Force workers had eaten in the CBD on Thursday and this person, who lives in the CBD and works all around that area, was symptomatic on Monday," she said. "So the timing looks absolutely right, that somewhere around there that transmission has happened."
Although more likely to be spread by close contact between people, Wiles said a surface like railings or doors could have been a point of transmission in this case.
"It is just really important that we keep using the [Covid Tracer] app so we can be informed really fast if we were exposed" - Associate professor Siouxsie Wiles
Genome sequencing can prove these instances take place and pin down exactly how it was spread.
She said it would be beneficial if sequencing efforts were faster and urged the government to use more Covid-19 genome sequencing facilities to speed up the process.
"At the moment everything gets sent to the Institute of Environmental Science and Research, and, depending on where a case is, that might mean several hours delay in order to get the sample to where it goes to sequencing.
"We may be able to speed that up by the fact we've got sequencing facilities all around the country. It may well be that we could shave off a few more hours and stop people having a night or so of worry."
She was hopeful no lockdown would be required, but said over the next few days people needed to take precautions, and get used to adhering to protocols like the covid app for the foreseeable future.
"It may well be that we have to move up to level 2 or something, which puts more emphasis on people doing physical distancing and these kinds of things.
"What we are also lucky with in this case is the person who did come forward with symptoms hasn't been to any big events, which would suggest there may be more cases. It is just really important that we keep using the app so we can be informed really fast if we were exposed."
Wiles said customers at the shop the woman worked at would have been informed immediately. The app and other protocols would need to be part of life for the next year, she said.
Auckland mystery Covid-19 case 'more like August outbreak'
Earlier, epidemiologist Michael Baker told Morning Report the latest Covid-19 community case had similarities to the outbreak in Auckland in August and there were likely to be other unknown cases.
Baker said it would be good news if there was a relatively short chain of transmission but it would not change the fact that there must be other unknown cases.
"Even if it's got the same genome sequencing as the Defence Force cluster that still doesn't tell us it definitely came from there.
"There could be some other source, still, because the lineages are not unique, necessarily.
"It helps, but we still want to know what are those other cases out there."
University of Otago epidemiologist Michael Baker. Photo: University of Otago, Wellington / Luke Pilkinton-Ching
Baker said there could be a number of cases.
"It's much more like the Auckland August outbreak that we had that was quite hard to control. It took a few weeks."
The University of Otago epidemiologist said some additional controls were needed, up to a potentially level 2-plus.
New Zealand's approach to previous outbreaks has been effective, he said.
"The distinguishing thing about New Zealand is a rapid, vigorous response to outbreaks ... and I think we'll need something similar here, unfortunately.
"It does work. It's tough - but I think now we should have instantly moved to something like a level 1.5. We don't have it yet but I think we should introduce it."
That could include limiting large public gatherings and making the use of masks on public transport mandatory.
"We should have instantly moved to something like a level 1.5" - Michael Baker
He said in effect there had already been an alert level change.
"As soon as you're saying to people work from home, wear masks and so on, effectively we are moving up the alert level system."