There are 49 new cases of Covid-19 in the community, bringing the total number of cases to 612.
Director-General of Health Dr Ashley Bloomfield said all of the new cases are in Auckland.
"It does provide further reassurance that our public health efforts are slowing the spread of the virus," Bloomfield said.
Of the new cases, 66 percent are family contacts, he said.
"Of the cases yesterday, only 23 percent are considered to have been infectious in the community."
Bloomfield said a Corrections officer at Springfield Corrections facility has tested positive for Covid-19 and 23 staff had contact with that person. All were isolating.
About 120 people in the Waikato facility were in contact with the person and they had been separated now, he said.
Inmates were also being tested.
The officer who tested positive was fully vaccinated and asymptomatic.
In this outbreak, 51 of the cases have not yet been epidemiologically linked.
Of today's cases, only 19 had not already been linked.
Prime Minister Jacinda Ardern said she wants the declining case numbers to continue to decline.
"We want the tail of this outbreak to be as short as possible," she said.
"Every day for me is another step, a bit of progress, but I want to see sustained reductions ... we've still got a journey to go through."
Of the current Auckland outbreak, six cases are under the age of one.
"If you can be vaccinated, be vaccinated on behalf of the tamariki," Ardern said.
There are 33 people in hospital, eight in ICU and two are being ventilated.
Bloomfield said none of the younger children infected in this outbreak are in hospital.
The youngest case in hospital is 18 years old. Bloomfield said most of those in hosptial are of an older age group.
Two thirds of the current cases are under age 30.
Yesterday, 16,755 tests were processed.
The high rate of testing is important for confidence about detecting any Covid-19 cases in the community, Bloomfield said.
"It's important for anyone who needs any kind of health care that they do it when needed. Do not delay care."
We may never find out how the virus got into the community in the latest outbreak, Bloomfield said.
Ardern said she laid awake at night pondering the ways in which it may have happened.
"Now were are left with theories without people-to-people contact," she said.
Yesterday the number of new cases slowed to 53 from 83 on Sunday and 82 on Saturday.
In announcing yesterday the two-week lockdown for Auckland, Prime Minister Jacinda Ardern said alert level 4 was making a difference but the job was "not yet done".