COVID-19 modeller's prediction of when cases could fall to single digits - and what it means for Auckland

As Aucklanders continue the hard mahi in lockdown while the rest of us bask in level 2, there is hope on the horizon, with one COVID-19 modeller predicting cases could fall to "single digits" next week. 

Whether that means Auckland could shift down to alert level 3 next week will depend on a few things. Yes, cases need to be trending down - but, as Director-General of Health Dr Ashley Bloomfield points out, it also depends on where those cases have been. 

"The number is expected to continue to fall," Dr Bloomfield said on Tuesday, echoing Auckland University disease modeller Shaun Hendy, who wrote in The Conversation: "On the current trend, case numbers could be into single digits next week." 

There's no doubt it's looking positive for Auckland, with barriers to reducing the alert levels slowly breaking away, such as the number of "mystery" cases not officially linked to the Delta cluster. Unliked cases fell from 33 on Monday to 24 on Tuesday.  

"Analysis of yesterday's 20 cases shows 17 or 85 percent were contacts of known cases and 16 or 80 percent were household contacts who were already isolating," Dr Bloomfield told the 1pm press conference. 

"Just four people were potentially infectious in the community with eight exposure events between them. None were in essential worker workplaces and none of these exposure events occurred after those people were asked to isolate.

"Clearly, all the numbers are moving in the right direction, which is reassuring."

What's the hold up then?

Moving too quickly, as we've seen in New South Wales, could be disastrous for Auckland, and we're already seeing the consequences of slip-ups. 

Middlemore Hospital has been forced to stand down 29 staff for 14 days after failing to isolate a symptomatic patient who later tested positive for COVID-19. 

It demonstrates just how quickly one hospital could become immobilised if the virus was able to get a foothold among staff - staff who are desperately needed to battle a serious outbreak. 

There are currently 39 COVID cases requiring hospital care in New Zealand. In New South Wales, there are more than 1100. With that kind of outbreak here, hospital resources would be stretched very thin. 

So, Dr Bloomfield's advice to Cabinet about Auckland will be cautious, but he will consider all of the elements of the outbreak, including that there does not appear to be evidence of cases not linked to the source: a returnee from Sydney. 

"All of the cases that have been sequenced in the outbreak - and it's the vast majority so far, except where sequencing has failed because there wasn't enough RNA material - they've all been clearly linked to the single introduction of this Delta case, and furthermore, there are a number of little variations that are helping to map the timeline of the outbreak," Dr Bloomfield said. 

"When we talk about cases not being epidemiologically linked, most of them are linked to other cases, and it's just there's no clear description of how they might link into one of the existing outbreaks or an earlier case, but it doesn't mean there's not a strong suspicion or that it is preventing the control of the outbreak."

Prime Minister Jacinda Ardern and Director-General of Health Dr Ashley Bloomfield.
Prime Minister Jacinda Ardern and Director-General of Health Dr Ashley Bloomfield. Photo credit: Getty Images

Dr Bloomfield said the current 24 mystery cases under investigation are a mix of historical cases from the beginning of the latest outbreak and newer ones. 

"The ones that are more historical from the outbreak we're less concerned about. We are much more interested in these latter cases," he said. 

"For example, of our 21 cases today, seven of those are new cases and one whānau. But it's finding out who was infected first in that whānau and then linking it back to a particular exposure, and there's some great work going on in that instance, to find out where the link probably is."

More than 39,000 contacts have been identified so far in this outbreak, and around 91 percent of them have been identified and had a test. 

Dr Bloomfield said for Auckland to come out of its strict lockdown, it will also come down to the level of testing. More than 7000 swabs were processed on Monday, the majority of which were in Auckland. But it pales in comparison to the more than 12,000 tests on Thursday last week. 

There could be a reason for that. Since we've been under lockdown conditions, we've reduced cold and flu to spread, meaning there are fewer people with symptoms. That has reduced the need for people to be tested. 

"Testing does remain central to us being confident the outbreak is under control in Tāmaki Makaurau," Dr Bloomfield said.

"The most important message from me today again is, if you have symptoms, please get tested in Auckland or indeed wherever you are in the country."