Associate Minister of Health Dr Ayesha Verrall admitted she is worried by the number of cases linked to Middlemore Hospital after a new emergency department patient was found to have Covid-19.
Wider testing meant the person was picked up today and tested positive.
Verrall was speaking to Newstalk ZB's Heather du Plessis-Allan.
She said the Government is "doing everything they can" to control the outbreak.
When questioned whether the outbreak was in fact "under control", Verrall said the Government is reducing uncertainty with the use of level 4.
"The thing with when you deal with an outbreak you are dealing with uncertainty, we can't test everyone every day to know about absolutely everything but we reduce that uncertainty by sticking to the level 4 lockdown rules," she said.
Verrall called the low numbers of unlinked cases a "good sign" and was adamant the current outbreak is close to being "under control".
Verrall was speaking after 13 new cases of Covid-19 were announced earlier today. The cases included a truck driver who tested positive after crossing Auckland's alert level 4 border.
The driver was tested after isolating for being a household contact of another case, director-general of health Dr Ashley Bloomfield said.
"I think the key thing to keep an eye on is most of our cases are coming from a handful of households now."
As well as being an MP, Verrall is also an infectious-diseases physician.
She said if there were any locations of interest linked to the positive truck driver, the locations will be released soon.
Listen live to NewstalkZB: Ayesha Verrall talking to Heather du Plessis-Allan
The truck driver travelled to Hamilton, Cambridge and Tauranga but it's unclear if he was infectious during that time.
There may be no locations of interest, Bloomfield said.
Twelve of today's 13 cases have been linked to the outbreak - the unlinked case was tested and discovered after they visited Middlemore Hospital.
Today, Jacinda Ardern said Cabinet has considered settings at alert level 1 and reached the conclusion that alert level 1 will remain the same, with no changes following the Delta outbreak.
From 11:59 this evening all permitted travellers across the Auckland boundary must show proof they have been tested.
The first mobile vaccine buses launched in Auckland this morning. Three launched this morning - one to Lincoln Rd and another at Papakura Station.
Experts warn the only way for New Zealand to avoid lockdowns is to have at least 90 per cent of the eligible population vaccinated.