Covid-19 Minister Chris Hipkins should resign over the sluggish vaccine rollout - but can't because Labour cannot find a good enough minister to replace him, says National leader Judith Collins.

And Collins is none too pleased with director general of health Ashley Bloomfield either, saying his "best" was "not good enough".

Asked if Hipkins should resign if a more capable minister was waiting in the wings, Collins said "exactly".

"At the moment, the problem is who would Jacinda Ardern replace him with - is there somebody else who's capable?" Collins said.

Collins said no one in Cabinet could fill Hipkins' shoes.

"I once thought a lot of Kris Faafoi, but look how hopeless he's been," she said.

"Stuart Nash has been stupid," Collins said, accusing the economic development minister of promulgating an "anti-vaxxer-type message" about vaccinations.

Nash, who has himself been vaccinated, has said the country would still lock down even if vaccination rates were at 80 per cent. He has not previously been accused of promulgating anti-vaccination messages.

"I can't see that there is someone more competent in all the people they've got - maybe Ayesha Verrall, maybe she could be, but it's not my job. I'm not the Prime Minister, it's not my job to pick her Cabinet," Collins said.

Collins said Hipkins might have "too much on his plate".

Hipkins is Minister of Education, State Services, and the Leader of the House, as well as Covid-19 Minister. Collins suggested Hipkins could drop the education portfolio to focus on Covid-19.

Collins was also unhappy with the Ministry of Health, and Bloomfield, its leader.

"We try not to personally go after the director general," Collins said.

"I think that Dr Bloomfield has done his best, but his best is not good enough," Collins said.

"He has an entire team of thousands, who are paid to do things; he's got a minister and he's got the Prime Minister with him and supporting him in everything he does - and he can't order the vaccine on time and get it into people's arms," Collins said.

"The Prime Minister may have confidence in him and so might the minister but I have to say we are starting to feel the gold gilt is starting to wear off," she said.

Collins was also scathing of the Ministry of Health.

"When you look at the Ministry of Health and the way in which they have completely cocked up this whole thing [the vaccine rollout], you have to wonder as to who's in charge," Collins said

"Now, standing up telling everybody 'look, be kind and be caring' and whatever - ultimately, you're dealing with a Ministry of Health and Government that failed to order the vaccine, failed to get the first order in until the 29th of January, failed to get it approved, failed to get all sorts of things done, and then failed to use GPs and pharmacists, who are the people in their communities that we trust," Collins said.

Collins would not say if she had confidence in Bloomfield.

"It's not for me to have confidence in him," Collins said, saying that it was for Ardern and Hipkins to decide.

Collins this week called for the Government to adopt a vaccination target to boost the level of vaccination in the country and reduce reliance on lockdowns.

The Government has been reluctant to set targets for vaccination or to give much clarity on when the country can move away from using lockdowns to combat outbreaks of Covid-19, particularly the more contagious Delta variant.

Collins said that she did not want to talk about an "acceptable" level of Covid-19 fatalities that she would tolerate after the country had been vaccinated, saying she did not like that terminology.

"Who wants to put their hand up to be one of those people? I don't want to do that and I don't think anyone does. So I don't like that whole terminology," Collins said.

"I am aware - as will be the Government - that every winter, barring lockdowns, we end up with 500 people dying from the winter flu.

"What we know is that that is what tends to happen when we have people who are unvaccinated and the virus comes through," Collins said.

She said this is what the future "might" look like, with Covid-19.

"It will be significantly worse if we don't get everybody vaccinated and we don't keep up those vaccinations," Collins said.