There are 20 new Covid-19 cases in the community - though only one is unlinked as Aucklanders cling to hope for an alert level change on Monday. 

Nineteen of the new cases are household or known contacts. 

The ministry said interviews were underway woth the unlinked case to determine how they were exposed, the Ministry of Health said in a statement. 

It said it was expecting fluctuations in case numbers at this point in the outbreak. 

Aucklanders were hoping for low numbers this weekend, before the Government on Monday decides whether the region can drop down to alert level 3. 

The ministry said testing at high levels in Auckland "remains an essential part of our outbreak response to detect every community case and stop onwards transmission". 

Another area of interest is whether there have been any cases linked to a supermarket truck driver who tested positive for Covid-19, after visiting a number of supermarkets in Auckland, Waikato and the Bay of Plenty. 

Several bakeries, petrol stations and other businesses outside Auckland have now been linked to the driver. The case emerged when a person in the driver's household was symptomatic and got tested. 

A positive wastewater result was found in East Auckland on Monday, and results from a follow-up sample are expected in the coming days. 

Meanwhile, a Covid-19 modelling expert believes lockdown fatigue may necessitate an alert level shift in Auckland next week, even though it risks stoking Delta's slow-burning embers. 

University of Auckland professor Shaun Hendy says Cabinet will be forced to balance the risk of further transmission with the consequences of prolonging lockdown when it meets on Monday. 

"You could persist at level 4 and stamp this out, I'm pretty sure that'd would be the case," Hendy told the Herald yesterday. 

"On the other hand, everybody's a bit over level 4, people need a bit of light at the end of the tunnel...it's probably worth taking a calculated risk." 

However, while confident exiting lockdown wouldn't be immediately catastrophic, Hendy said relaxing restrictions while the virus circulated in the community could have consequences. 

"If we're still seeing consistent community transmission then by going to [level] 3, you just give [transmission] the opportunity to speed up. 

"If you're accepting that we may need to go back to level 4 in some time in October, then shifting to level 3 is a low-risk option." 

Yesterday, director of public health Dr Caroline McElnay said there was "cautious optimism" the vast majority of the outbreak had been contained, despite eight of the outbreak's active cases yet to be epidemiologically linked, including the case identified at Middlemore Hospital on Thursday. 

Deputy Prime Minister Grant Robertson said yesterday testing rates had been very good this week, but the Government would not set a number on what was needed to move alert levels. 

"We absolutely appreciate the fact that Aucklanders have been through five weeks of this, and it is hard, and we thank Aucklanders for that. 

"Keep the faith...what we've done under alert level 4 has worked." 

Another important statistic to be released is the latest vaccination figures. As of yesterday, 73 per cent of the eligible population has had at least one dose of the Covid vaccine. 

The Herald and NZME have launched a campaign, The 90% Project, to work for at least 90 per cent full vaccination against Covid-19 in our eligible population by Christmas.