The Ministry of Health released a statement regarding the new case at the border on Monday evening. The test was done as part of routine surveillance testing.
"The information available indicates the worker is asymptomatic. Further investigation is being undertaken this evening," the ministry said.
"The managed isolation worker and their immediate household members are isolating at home in Auckland this evening.
"Additional tests and whole genome sequencing are currently being arranged."
There is a noticeable security presence outside the hotel this morning, with two guards wearing masks at the entrance.
On the Unite Against Covid-19 Facebook page, a staffer - in response to a question - defended the decision to keep the family isolating at home rather than having them in quarantine.
"Please remember that Covid-19 is the problem, not the people who have it. The decision to isolate at home or in a facility is specific to the case and their household's needs and personal circumstances - this is a decision made by a local medical officer of health. The case and their household may yet be transferred to a quarantine facility tomorrow - we will share any information around this as soon as we receive it," the staffer wrote.
The ministry has not added any new locations of interest to its website overnight.
It has also not confirmed if the infected worker had received their first vaccination against Covid-19.
Contact tracers were last night working with the infected hotel worker to determine if there were any locations of interest.
The Grand Millennium Hotel was also the facility where a worker was sacked after a bedroom encounter with a returnee.
The employee lost their job after a 20-minute encounter with a person who was undertaking their mandatory 14 days of isolation.
MIQ head Brigadier Jim Bliss described the forbidden hotel liaison on January 7 as "incredibly irresponsible and extremely disappointing".
The hotel worker and returnee both returned negative Covid-19 tests before and after the encounter. Bliss said health officials deemed the risk of spreading Covid in the community as negligible to low.
Meanwhile, the Government is currently vaccinating all frontline border workers against the virus in the first round of a mass vaccination programme to protect New Zealand from the global pandemic.
The Herald has sought comment on the latest case from Covid Response Minister Chris Hipkins.
On the Unite Against Covid-19 Facebook page, the staffer said they did not know the person's vaccination status.
They added in another comment: "The vaccine requires two doses and takes around two weeks until it begins to provide protection. The second dose is given at least 3 weeks after the first."
The staffer said while many MIQ and border workers had received their first dose, many were yet to receive their second. "The Pfizer/BioNTech vaccine has shown to be approximately 95% effective against symptomatic Covid-19, 7 days after receiving the second of the two doses."
In a reply to another Facebook user, a staffer also said the case would likely "be counted as an imported case because it was most likely caught through their work in MIQ".
"Contact tracers are working with the case to determine whether there are any locations of interest. We will have more information tomorrow."
Today marks exactly one year since the nation was plunged into its first lockdown.
Prime Minister Jacinda Ardern announced at 1.30pm on March 23, 2020 that New Zealand would move to alert level 3 effective immediately, and to level 4 in 48 hours.
Last week the Herald reported that the Grand Millennium Hotel had been instructed by the Government to stop charging guests for penthouse suite upgrades.
It came after it was reported in December that the hotel had upgraded two families who were undergoing 14 days' MIQ to the hotel's top-floor apartment, with officials saying the cost associated with the stays was borne by the families and "payable to the hotel".
After learning of the paid upgrades MIQ bosses told the hotel to cease the practice which was outside the hotel's contract.
