The Auckland airport worker who tested positive for Covid-19 yesterday cleaned a plane that brought a returnee with the virus back to New Zealand on April 10.

And she cleaned a "green-zone" plane that flew from here to Australia on Monday, the day the quarantine-free trans-Tasman bubble started.

But Covid-19 Response Minister Chris Hipkins said it was normal protocol to allow workers to work both red and green zones at the airport on different days, and strict measures were taken to prevent them getting infected.

"They leave work at the end of the day. They go home to their family and they are free to move about in their communities," he said.

"It's very difficult to say that they can go to a concert or a public event, but they couldn't go and work in the green zone."

Australia used the same protocols, he said, and workers typically didn't move from the red zone to the green zone in a single shift.

The risk of someone cleaning a plane passing on Covid-19 is "minimal, if there is any at all".

Director of public health Dr Caroline McElnay added: "Our assessment is there is no additional risk to any passengers who travelled on those flights cleaned by the infected person."

How the cleaner was infected was still being looked at, and there are no new locations of interest so far beyond the three that were released yesterday.

Hipkins confirmed that the genome sequencing showed a match with the cleaner and an infected returnee from Ethiopia who travelled via Dubai.

The cleaner was wearing full PPE, including an N95 mask, and person-to-person contact between the cleaner and the passengers on the flight hasn't been ruled out yet.

There were no new cases linked to the airport worker, who was last night moved to the Auckland quarantine facility.

The plane cleaner, who works for Menzies, worked three shifts during their infectious period with a number of colleagues, and officials are working to determine who is a close contact from their interactions.

Currently there are 25 close contacts, 17 of whom are workplace contacts, and the seven tested so far have tested negative, while one is being followed up.

Others will be tested on day five.

McElnay said there were no new community cases to report, and one new case in MIQ, who arrived from Switzerland.

There have been 183,351 doses of the Pfizer vaccine administered as of yesterday, including 140,580 who had had one shot and 42,771 people - including Hipkins himself - who had had two doses.

He said 41 per cent of those vaccinated with one dose were in Auckland, 19 per cent of whom were Maori or Pasifika.

But only 7478 out of 50,000 household contacts of border workers had had two doses, and Hipkins encouraged those people to get vaccinated.

"I'd like those numbers to be higher - please do come forward and get those vaccinations. You are able to get these now."

He said it was "ambitious" to be able to get 534,000 doses administered a week at the height of the vaccine roll-out.

As the roll-out progressed, it was important for people to come forward, book in, and to show up when they're booked in.

Asked whether we were 20,000 doses behind schedule, Hipkins said there was a vaccine targets that had been released didn't line up with the same timeline as the weekly vaccine updates.

We were, in fact, slightly ahead of schedule, he added.

No audit done on border employers

Hipkins said he is writing to the chief executives of all the agencies working at the border to remind them of their legal obligations, including making sure their workers are being tested and that they keep records of those tests.

But he conceded there had been no system-wide audit of the hundreds of border employers, meaning the Government was relying on employers to be its eyes on 15,000-odd border workers who need to be regularly tested.

Asked why an audit hadn't been done to ensure compliance, he said: "Just the practicalities and the potential expense involved in doing that."

He said he would look into whether such an audit could be done.

"But ultimately the legal requirement is clear. People need to follow the law here. We don't audit every New Zealander to determine whether or not they are following the law."

Asked about ground crew interacting with passengers and not being regularly tested, he said he would like to see evidence of that because it meant employers weren't meeting their obligations.

Asked about a man in Brisbane taken to hospital three days after getting the Pfizer vaccine, Hipkins said that blood-clotting was not commonly associated with the Pfizer vaccine.

"Cause and effect here can sometimes be difficult to establish. People do get blood clots unrelated to vaccines."

McElnay said the ministry was monitoring what was happening with the Pfizer vaccine around the world.

'Bin it'

Hipkins addressed people handing out professional-looking material to undermine mask-wearing on public transport, which he called "potentially dangerous".

A rubbish bin was the "only fit place" for those pamphlets, he said.

"Mask-wearing is simple, it's effective and it helps to keep us all safe."