Prime Minister Jacinda Ardern says border workers have up to the end of April to be vaccinated before they are moved out of their jobs.

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 says a voluntary register of border workers to record testing and vaccinations should be a mandatory requirement for all employers with border-facing staff.

And he says there appeared to varying estimates, between 80 per cent and 95 per cent, of how many border workers had been vaccinated.

Questions about just how many border workers have not been vaccinated were triggered by last week's positive case of a privately employed security guard working at the Grand Millennium managed isolation hotel – who had missed two vaccination appointments.

Ardern said on Thursday that from Monday, unvaccinated border workers would start being moved to other work.

Today on TVNZ's Q+A, she said they would have up to the end of the month to be vaccinated or moved.

"We are moving into the phase where the window is closing … we have already set down that the period from Monday through to the end of this month - if in that period they are not vaccinated, they are redeployed," she said.

"That is really is last call. We had always planned that this would be the period in which that would happen."

But National's Covid-19 response spokesman, Chris Bishop, said if border workers had not had at least one of their two doses of vaccine by now, they should be moved off the frontline.

"It should be a very clear and immediate rule," he said.

"There has been more than enough time since the vaccination programme started with the border workers to get vaccinated. Most people say that's a reasonable amount of time.

You are vaccinated and if you're not, you can't work on the frontline."

Bishop said there were varying estimates as to how many border staff had been vaccinated.

It also appeared the Government did not know exactly how many people worked at the border and that added to the confusion.

"But if you assume that between 80 per cent and 95 per cent of border workers have had a jab, then now is about the right time to say if you are going to work at the frontline you have to be vaccinated. It certainly shouldn't take until the end of April to do it."

Bishop said the Government needed to have better information about the frontline border workers.

While there would always be people coming and going from the workforce, it needed to have a reasonable handle on how many border workers there were on a day to day and weekly basis.

Commenting on a Newshub report that Covid-19 Response Minister will soon make it compulsory for every border worker to be part of a Border Worker Register, he said it was "past time we had that."

After the outbreak in February, most people would have expected the Government had strengthened the oversight with a compulsory register.

"It is a mixture obviously of state and private sector employees but Mr Hipkins can use a public health order to establish a register and make it mandatory to participate in that register. He should do that."