The latest MIQ worker who tested positive for Covid-19 was also not vaccinated, director general of Health Ashley Bloomfield said.
It comes amid revelations that 20 per cent of border staff have yet to get the jab protecting them against coronavirus.
Bloomfield said he understood that the latest case - who works as a security guard at the Grand Millennium MIQ facility in Auckland - wanted to get the vaccine but was in isolation.
Bloomfield said there was no problem with vaccine supply and he felt confident about the vaccine rollout.
The fresh case was a contact of another security guard at the hotel who had earlier tested positive for Covid-19.
Five out of eight of the first security guard's close contacts had tested negative. The three remaining were still awaiting test results. The first security guard tested positive for Covid-19 last week. The second security guard tested positive over the weekend.
The infections are genomically linked to a cleaner at the Grand Millennium who tested positive in March.
The cleaner and the first security guard are genomically linked to a returnee who arrived back in New Zealand on March 13.
Seven cases in MIQ today
There are seven new cases of Covid-19 in managed isolation, Bloomfield said. Three of those are linked to existing cases, he said.
MIQ Brigadier Jim Bliss said his team will continue to review his processes and no findings had come out of that audit.
Bliss said the security guard was not tested in the "period of infection". The man's last test was April 8.
"It is a concern ... and we will have to look at strengthening that process," Bliss said.
Bliss said his team was still investigating when the security guard was last tested but he was concerned it wasn't within the 14-day testing policy.
Bloomfield said they hadn't been able to identify a date between the middle of March and April 8 that Case B was tested and "it is a concern".
Bliss said said 98% of staff at the facility has been tested and he expected the remaining 2 per cent to be by the end of the week.
He said the focus was now on established the cause of infection.
Bliss said when MIQ started officials were using pen and paper - now they use a system where staff sign and answer a bunch of questions.
That data is now been used to populate the MIQ testing regime. We are now investigating the accuracy of that date, Bliss said.
20 per cent of border workers still don't have jab
Bloomfield said there are many people at the front line who have been vaccinated - everyone has been invited to be vaccinated but no everyone has taken up that offer.
He said they had seen high uptake. About 80 per cent of border workers have been vaccinated and we are working to ensure the rest are vaccinated by the end of the month.
"It's very difficult to pin down how many people haven't been vaccinated."
If front line staff can't be vaccinated then they need to move into other roles, Bloomfield said.
His expectation is that the ministry will make it very easy for these workers to be vaccinated by the end of the month, he said.
"You can't immediately withdraw 20 per cent of your workforce ... so we are now working to ensure they are vaccinated by the end of the month."
Bloomfield said the reasons people aren't getting the vaccine was either personal or logistical.
Those people who have refused to get the jab will be at the head of the queue to have a conversation with their employer about redeployment, Bloomfield said.
"We don't have numbers."
"It's no a straightforward process," he said.
Bloomfield suggested that a MIQ worker who has refused the vaccine and made that clear to their employer could still continue to work on the front line. "It's not a one off conversations, it will be a series of conversations with their employer."
Bliss said May 1 will be a very important date and it's his expectation, and the Government's, that all MIQ staff will have their first vaccine dose before being able to work.
Bloomfield said a border worker testing register will be able to determine staffs' vaccination status and employers will be able to use that to check on whether or not they had received the jab.
The latest case at Grand Millennium
Last night, health officials revealed another worker, who has been stationed at the Grand Millennium MIQ facility, tested positive for Covid-19.
They were a close contact of the security guard, who tested positive last week, and had initially tested negative.
But they had also recently been working at the Grand Millennium.
Asked this morning if this person had been vaccinated, Ardern couldn't say.
This was something she said she would be leaving to Bloomfield to explain this afternoon.
The Government has come under pressure after Bloomfield admitted last week that the security guard who tested positive had not been vaccinated.
There were "logistical issues", he said at the time – later, health officials revealed the person had missed two appointments to get the Covid jab.
Ardern said this morning that 79 per cent of all First Security staff – one of the companies hired by the Government to work at MIQs – had received a vaccination.
That, Ardern told TVNZ, was "not good enough".
"Everyone in MIQ has to be vaccinated."
First Security said in a statement that it had met all "government mandated Covid-19 health and safety obligations and requirements".
"We have done, and continue to do everything possible to ensure all employees working at MIQ facilities are vaccinated by the 30 April deadline set by the Ministry of Business, Innovation & Employment (MBIE), whilst acknowledging employee rights," he company said.
"All First Security staff working at MIQ facilities are aware that they must be vaccinated by the 30 April deadline to continue working at these facilities.
"Staff who are unable to attend an onsite appointment during a shift are paid to attend an appointment outside of working hours."
Ardern said 80 per cent of all MIQ workers contracted by the Government have received the vaccine.
"The expectation is that there will be no one who is not vaccinated working on the frontline by the beginning of May."
This is an area where Bloomfield and Bliss will be questioned by reporters today.
They will be asked to provide a clear explanation of the Government's strategy when it comes to the vaccination of private frontline staff.
The pair is also expected to provide an update what has happened, and what will happen, to any Government employees working on the frontline who have not got the jab.
Ardern has said border workers have up to the end of April to be vaccinated before they are moved out of their frontline jobs and into a position elsewhere.
But National's Chris Bishop says the rule should be applied from now on, not the end of April, considering border vaccinations began on February 20.
He also said that a voluntary register of border workers, which would record testing and vaccinations, should be a mandatory requirement for all employers with border-facing staff.