Dr Clark has weathered repeated calls for his resignation this week, after news two sisters who subsequently tested positive to Covid-19 had travelled from Auckland to Wellington on compassionate grounds.
A third person returning to New Zealand from Pakistan has also tested positive to Covid-19 this week.
The Dunedin North MP told the Otago Daily Times yesterday he was not distracted by people calling for his head.
"The Prime Minister has been clear that the responsibility for this operational error sits with those who did not do as ministers were clearly lead to believe was happening," Dr Clark said.
"My colleagues are very clear that this is an operational matter, I am very clear that this is an operational matter, the director-general [of health] himself has apologised because he has acknowledged that the system has failed."
The women should have been tested before leaving Auckland under Covid-19 control protocols but were not.
Their case has proven to be one of many deviations from the regulations, revelations which earlier this week prompted Prime Minister Jacinda Ardern to place the Defence Force in charge of border security and quarantine.
Yesterday, Housing Minister Megan Woods — who already had responsibility for temporary accommodation provided for quarantining travellers — was given ministerial responsibility for border control.
Dr Clark said it was frustrating quarantine protocols were not followed.
"I am angry that they haven’t been. I know that I and other ministers had a clear expectation that the protocols in place would be followed and for good reason.
"When I found out that they weren’t I moved very quickly to end the compassionate leave exemption. Obviously that is not a decision that anyone takes lightly, but I just did not feel that after the efforts and sacrifices of so many that we could place those gains at risk."
The protocol breaches have suggested tensions between politicians and officials managing the country’s fight against Covid-19, but Dr Clark was confident all decision makers were collaborating effectively.
"There is a very good working relationship across leadership, but it is a robust relationship and when mistakes are made, direct conversations need to be happening and they need to be happening quickly," he said.
"My decision to suspend compassionate leave exemptions was made very quickly because quick action is the thing that has put New Zealand in this place, it is the thing we need to ensure continues. New Zealand went hard and early, that is why we are in such an enviable position internationally, but there is no room for complacency."
No new Covid-19 cases were reported in New Zealand yesterday, but Dr Clark expected more cases of the pandemic disease would be detected.
"I would expect that we would have more cases arriving at our border over time because Covid-19 is spreading around the world at record levels," Dr Clark said.
Yesterday the Ministry of Health closed two significant clusters of Covid-19 cases, those associated with a wedding in Bluff, and those stemming from Rosewood rest-home in Christchurch.
