Public health officials expect that the peak of new delta-variant covid-19 cases is still to come after confirming 21 new cases today, mostly in Auckland.

Contact tracing efforts will be focused in Auckland and Waikato, with the number of close contacts expected to rise to 10,000 by the end of today, although 266 other close contacts at the time of this afternoon’s update are in the rest of the country.

The escalating number of close contacts coincides with a record number of tests being processed – 41,464 yesterday – and prime minister Jacinda Ardern said the number of positive cases is expected to keep rising. Of the 21 new cases confirmed today, 18 are in Auckland and three are in Wellington.

“We haven’t peaked yet, that’s our view, and I think that’s important to share with people so they know what’s likely to occur,” Ardern said in the government’s 1pm update.

“That doesn’t mean that the strategy of our lockdown is somehow unsuccessful. That is to be expected.”

Ardern said she still expects that Auckland will go beyond the initial seven-day period – as advised by health officials – but said she’ll wait until ministers have all the evidence in front of them on Monday before giving any indication on restrictions in other areas.

Several supermarkets in both Auckland and Wellington have been identified as locations of interest, and Ardern said commerce minister David Clark is in discussions with operators to ensure their supply chains stay up and running.

“He is talking to them about the kinds of contingency they have in place,” she said.

The government is standing up more testing sites to cope with the wider net cast to capture the impact of the more infectious delta strain, including specific sites for close contacts only.

Even with increased testing capacity, health officials administered a record 56,843 vaccine doses yesterday, and Ardern said 72% of New Zealanders aged 40 and over are either booked to receive a vaccine or have received at least one dose.

Covid-19 response minister Chris Hipkins will front tomorrow’s briefing before cabinet meets on Monday to decide whether to lift some covid restrictions once the national lockdown ends on Tuesday night. Ardern indicated an extension of level four rules was almost inevitable for Auckland at least.