The Ministry of Health has revealed three locations of interest relating to the border worker at Auckland Airport who has tested positive for Covid-19.

The person works as a cleaner at Auckland International Airport, cleaning planes that have flown internationally from countries where Covid-19 is widespread.

They tested positive yesterday, the same day the transtasman travel bubble came alive.

The three locations of interest identified so far are:

• Westfield St Luke's Food Court, Saturday 17 April 2021 12:15pm to 2:30pm
• Bunnings New Lynn, Saturday 17 April 2021 2:30pm to 3:50pm
• Movenpick Dominion Road, Saturday 17 April 2021 5:15pm to 7:20pm

Sixteen close contacts have been identified so far.

The worker had been tested weekly for Covid-19 as part of routine surveillance testing. They were tested yesterday at their workplace and that test came back as positive today. Their previous tests were all negative.

"The person is currently isolating at home while they are being interviewed by health officials and following this they will be transferred to the Auckland quarantine facility," the Ministry said.

"Five household contacts have been tested and have returned negative results. Close contacts from the person's workplace are being identified, isolated, and tested.

"So far, we have identified that the person has 16 close contacts. This number will likely change as further scoping of this person's movements identifies other people they have been in close contact with."

It comes after a border worker at Auckland Airport returned a positive test for Covid-19 just as the transtasman travel bubble came alive on Monday.

Prime Minister Jacinda Ardern said the latest Covid-19 case was a vaccinated border worker who came into contact with planes from "high-risk" countries.

Ardern confirmed the person was fully vaccinated. They were regularly tested - the last time on the 19th.

She said the person was working in a "high-risk" area cleaning planes.

"That is a place where workers ... need to be tested and vaccinated," she said, but also "thanked".

The person was negative on the 12th - they were picked up during routine testing, Ardern said.

She had not spoken to Australia's PM Scott Morrison - but Chris Hipkins has talked to the Australian Health Minister about the case.

Ardern said she had always said there would be cases - "Australia accepts that".

On the border worker, Ardern said this was an important opportunity to say the vaccine is 95 per cent effective.

That means people can still get Covid, but it won't be as bad as it otherwise would have been.

"It is working as intended ... it's doing it's job," she said of the vaccine.

She said people who have the vaccine will still get Covid; but they won't get as sick and die.

She said the vaccine reduces the likelihood of passing on the virus. "The vaccine is saving lives," she said.

She denied New Zealand has a leaky border, given the worker who has Covid was cleaning high-risk planes.

She said further contact tracing and locations of interest will be unveiled soon.

More information is still being sought, including where the plane the worker cleaned had come from.