All of those close contacts are exclusively employed at the airport in non-public facing roles.
Under the terms of the trans-Tasman bubble agreement, all states, territories and New Zealand can suspend quarantine-free travel with places that have outbreaks.
"We know the Pfizer vaccine is highly effective, but at 95 per cent effectiveness a small number may not be protected".
The Ministry thanked the worker who, "like many others at our border, have worked in an environment during this pandemic that has exposed them to the virus that we have collectively worked so hard to keep out". "In this case there is", Ms Ardern said.
The Prime Minister added that the bubble is a world first and everyone should take a moment to be "very, very proud" of what she described as "a team effort" to reach this point.
"It's a win-win for Australia and New Zealand", he said.
However, no sooner were the emotional reunions of loved ones a fact than an airport worker in Auckland tested positive for COVID-19.
Ardern said both countries had expected there would be cases of Covid-19 among border workers while the trans-Tasman bubble was open.
Mr Ardern said the isolation of close contacts of the airport worker was underway.
They must not be awaiting the results of a Covid test, nor have any Covid symptoms, amongst other criteria.
Emotional reunions as Australia and New Zealand open travel bubble
Air New Zealand executive Craig Suckling said the atmosphere at Sydney airport before departure was electric. Victoria recorded zero new local cases of COVID-19 on Sunday, with four new cases in hotel quarantine.
"In situations like this a lot of pressure gets put on aviation workers and airport workers. sometimes there's a lot of blame put onto them".
"I think everyone's been feeling very constrained, shut down, hemmed in, and the opportunity to actually go somewhere for a holiday [.] is something that now seems such a luxury that it's made an enormous difference to people's psychology".
There are no new cases of Covid-19 in the community today, it said.
"This case is a recent returnee who is considered recovered", say the MOH.
Since 1 January 2021, there have been 49 historical cases, out of a total of 425 cases.
The seven-day rolling average up to yesterday is 4,254 tests processed.
The case appears to be unrelated to the travel bubble though and flights with Australia have not been suspended.
One was part of a bubble with two previously reported cases and had been transferred to a quarantine facility on 4 April.
The person has been placed in isolation, interviewed, and their contacts are being tracked, New Zealand Health said Tuesday.