Jacinda Ardern says actions of latest COVID-19 cases had 'devastating' consequence

Prime Minister Jacinda Ardern is fuming over the actions of the latest COVID-19 cases, which she says had "devastating consequences".

On Monday morning Ardern revealed how people from two separate families contracted the virus.

"Both family members from both households had contact during level 3 - that's what has occurred," she told The AM Show.

She says the first family was asked to isolate once they had tested positive and was interviewed.

"That interview did not disclose the contact. Whether or not they forgot or lied I cannot tell you but either way it has had a devastating consequence."

She says the families breached public health guidance "multiple times" by not isolating when they were feeling ill, not isolating after getting tested and not disclosing their contact with one another. 

She told The AM Show she was absolutely angry at how the situation transpired - but said it was paramount that the families not be vilified for what she called a "dumb" decision.

"We are not going to get through this if every time someone does something dumb we pillary them to the point that people are fearful and they don't tell us the truth."

She declined to comment on whether the families should face legal action, saying she was "glad" it was not her decision to prosecute those who break the rules, as she is between a rock and hard place when it comes to protecting the population.

"Do I want people to understand the consequences? Yes, but my job is twofold - first, to prevent people dying and second to get people to follow the rules.

I find this a difficult dilemma and that's why I'm pleased it's not my decision."

The latest COVID-1 case plunged Auckland into level 3 lockdown by not isolating after they were tested. They went to a gym, a supermarket and attended university which Ardern says created "multiple high risk" locations.

Auckland will remain in alert level 3 until at least Sunday, and the rest of the country is at alert level 2.