Prime Minister Jacinda Ardern is being questioned on the vaccine rollout at MIQ facilities, after the revelation two new border-related cases hadn't been vaccinated.

At a press conference this afternoon, Ardern said 86 per cent of front-line workers had been vaccinated so far. More information would be given on Wednesday.

Those who aren't vaccinated will be moved off the frontline by the end of the month, she said.

"That's a timeline that's been set out for some time."

She said there were now 3472 MIQ workers vaccinated out of 4010 workers. Seventy-nine per cent of First Security's MIQ workforce has been vaccinated.

Ardern began the press conference by acknowledging the death of Prince Philip, the Duke of Edinburgh. There were three condolence books at Parliament and one at the National Library, she said.

A state memorial service will be held at 3pm on April 21 in Wellington.

Ardern and Director-General of Health Dr Ashley Bloomfield have come under increasing pressure in recent days, after it was revealed two unvaccinated private security workers caught the virus.

Speaking to media earlier this afternoon, Bloomfield said there was no suggestion that either security worker was hesitant to take the vaccine.

The first on – case B who was diagnosed with Covid last week – had not been able to make it to two appointments.

The new case revealed last night – case C – did want to get the vaccine but was unable to as they were in self-isolation; given they were a close contact of case B.

Both workers were employees of First Security – a private security firm contracted by the Government to work at the Grand Millennium MIQ facility.

In a statement, First Security said it has met all the Government's Covid-19 health and safety obligations around MIQ.

"We have done, and continue to do, everything possible to ensure all employees working at MIQ facilities are vaccinated by the April 30 deadline set by MBIE, whilst acknowledging employee rights."

Asked why there were still MIQ and frontline workers yet to be vaccinated, Bloomfield said: "Because it's a large workforce".

He said that all workers have been invited to receive the jab but some have yet to "take up that invitation".

"It was always envisaged that there would be a period that they [MIQ and frontline workers] would be given to take up the invitation."

Workers have until the end of April to get vaccinated.

If they don't get the jab by then, "other arrangements would need to be put in place," Bloomfield said.

The vaccination campaign for frontline workers began on February 20 and so far, 80 per cent of First Security

But Bloomfield was unable to say exactly how many frontline border workers have received the vaccine yet.

This is something Ardern is likely to be pushed on.

Ardern said this morning that roughly 80 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.

"The expectation is that there will be no one who is not vaccinated working on the frontline by the beginning of May."

As well as questions around Covid-19, Ardern is also likely to share a few comments about the passing of Prince Philip – the Duke of Edinburgh.