The 13 cases are all in Auckland, linked to the four people who tested positive for the virus earlier yesterday.
“Given that they are linked, we are treating them as a cluster and we fully expect there to be new cases,” Dr Bloomfield said.
One of the recent incidents is that of a pupil at Mount Albert Grammar School in Auckland.
The guy, while at school, was asymptomatic and hadn’t attended since becoming unwell.
Dr. Bloomfield said the risk to other students and teachers was “low at this point but we are taking all precautions”.
At Americold, a trendy store business in Mount Wellington, three of today’s new cases are workers. About seven of those workers are family members.
The two locations of the business-Auckland Airport and Mount Wellington-are now closed.
Another positive case today is an employee at Finance Now. It grows before it slows’
Prime Minister Jacinda Ardern said the additional 14 cases of coronavirus demonstrate “the seriousness of the situation” today.
“While it is serious, it is being dealt with in an urgent but calm and methodical way,” Ms Ardern said.
“As we all learnt from our first experience with COVID, once you identify a cluster, it grows before it slows. We should expect that to be the case here.”
Auckland’s stage three lockdowns are “giving us a helping hand” in curbing the spread of the virus, she said.
“It means when we’re contacting people, they’re already observing restrictions that limit the spread of the virus.
“You would have heard there’s more information we need to find, such as the source, what we refer to in a cluster as the index case.
“We have managed to contain clusters before without identifying the source.
“But knowing where it has started does give us that extra confidence that we have reached everyone we need to in order to stop transmission.”