Jacinda Ardern is warning Kiwis the worst in New Zealand's Delta outbreak of COVID-19 is yet to come after another jump in cases.
On Saturday, NZ recorded 21 fresh community cases, the country's worst single day for transmission since April last year.
The outbreak remains centred on Auckland (45 cases overall, 18 on Saturday), though it has spread south to the capital Wellington (six overall, three on Saturday).
Saturday is day four of a national lockdown which will probably need to be extended beyond the planned seven days.
The number of potential exposure sites has grown to more than 200, and the number of close contacts of existing cases exceeds 5,000.
Director General of Public Health Caroline McElnay said close contacts would exceed 10,000 by the end of Saturday.
Ms Ardern reasoned with Kiwis to remain calm as numbers spiked.
"The number of cases has grown again but given the large number of locations of interest and what we know about Delta, this isn't surprising," she said.
"We've always said cases would rise before they fall. We do expect cases to continue to rise through to next week before they start falling away."
Ms Ardern said she was reticent to share "variable" modelling data which might predict the peak of the outbreak.
All cases have either been linked to the same source, or appear so, based on initial assessments.
Officials believe the source of the outbreak is a border failure: a leak of the virus from a man from Sydney during his stay in a quarantine hotel facility earlier this month.
A man in Christchurch doing some early morning exercise on an empty street. Source: Sipa USA Adam Bradley / SOPA Images/Sipa
A large proportion of the infected are young people under 30.
NZ, lauded internationally for its successful COVID-19 elimination strategy, had enjoyed 170 days without community transmission until Tuesday.
Until this week, it had not encountered Delta - the same variant which has pushed cases in Sydney beyond breaking point.
Despite the rampaging outbreak, there are signs NZ may meet the challenge.
On Friday, the country beat its own record for most vaccinations administered in a day: 56,843, more than one per cent of the population.
However, NZ's overall vaccination rate remains low, slipping behind Australia's stuttering rollout.
Just a third of Kiwis have had at least one jab and less than a fifth are fully vaccinated with two.
NZ is relying upon Pfizer for its initial rollout, which it hopes to complete this year.
The other promising sign Ms Ardern lauded was the most COVID-19 tests processed in a single day - 41,464 - showing Kiwis' ability to respond to the growing crisis.
"This is exactly what we need to do get on top of this outbreak, but also to prepare us for the future," Ms Ardern said.
Ms Ardern's government will meet on Monday to decide its lockdown settings beyond Tuesday.
