The airport worker was infectious from January 15 - but they were not at work while infectious.
The case has one household contact who has returned an initial negative test result.
The first of the locations of interest linked with this case were being published on the Ministry of Health website.
A further 15 contacts among the Stamford Plaza staff are currently isolating at home as contacts of the MIQ worker with Omicron and their co-worker.
The worker's household contact who returned a positive test yesterday is isolating at home.
Two other household contacts are symptomatic but returned negative tests yesterday.
The border worker's co-worker who is symptomatic remains in MIQ and has returned a further negative test.
Whole genome sequencing has linked the border worker's infection to a person who arrived in New Zealand on a flight that landed on January 8 and tested positive on day 1, January 9, of their stay at the Stamford Plaza and was transferred to MIQ on 10 January.
As of this morning, 84 contacts had been identified in relation to the MIQ border worker.
At this stage, 79 had returned negative test results and one household contact has returned a positive result, which was reported yesterday.
The ministry said in a statement that the number of contacts could fluctuate as further investigation rules them out.
Of the contacts identified in relation to the two bus journeys, there were four contacts that were yet to be reached
Two of these contacts have returned a negative test from following advice on the Locations of Interest web page or advice from a mobile phone notification, the ministry said.
While these exposure events were a low public health risk, further efforts to reach all outstanding contacts were being made.
The Ministry of Health also provided an Omicron update, saying there had been 370 Omicron Covid-19 cases detected at the border since December 1 - and 32 of the Delta variant.
There were also 203 Covid-19 cases caught at the border that were still undergoing whole genome sequencing, the minisry said.
"The expectation is that the vast majority will be the Omicron variant."
A total of 27,730 children aged 5–11 have received the first dose of the vaccine. This is 5.8 per cent of all children in that age group.
Yesterday, 38,606 boosters were given - bringing the total to 828,215, which is 51 per cent of those who are now due their booster.
Overall, 1,222 first doses of Covid-19 vaccines were administered yesterday and 2,318 second doses were given.
Eighty nine per cent of eligible Māori people had received their first dose of the vaccine, and 84 per cent were double-dosed.
Today's cases
Fourteen of today's new cases are in Auckland.
There was one new case in Waikato - which was in Hamilton and was being investigated for a link to a previously reported case.
In Waikato, pop testing sites were operating in Ōtorohanga,Te Kūiti, Ngāruawāhia, Morrinsville, Huntly, Taumarunui, Tokoroa, Putāruru and Hamilton today.
In Lakes, there were five new cases, all in the Rotorua district.
Four of these cases were linked to previously reported cases, and one was still being investigated to determine any links.
There was also one new case in Tauranga, Bay of Plenty, and investigations were underway to determine a link to known cases,
In Hawke's Bay, the Ministry of Health confirmed a further two Covid-19 positive tests had been returned for Hastings residents, taking the total number of active cases in the region to four.
The ministry said one of these cases was notified after the daily reporting cut-off and would be included in tomorrow's official case figures.
Both cases were linked to a previously reported location of interest, the Tu Step Fitness Class at the Ascende Global Church in Hastings.
Investigation into the cases' movement were continuing while public health officials also continued contacting any close contact.
Any new locations of interest linked with the Hawke's Bay cases would be published in the Ministry of Health contacting tracing locations of interest webpage.
Covid-19 Response Minister Chris Hipkins is set to hold a press conference at 2.45pm to explain why the latest MIQ room release was unexpectedly postponed last night to the dismay of thousands of stranded Kiwis.
The Ministry of Health is set to release its latest update in a statement at 1pm today.
Yesterday there were 14 new community cases but 30 cases of Covid-19 detected at the border.
There were 30 people in hospital with just two in intensive care.
Meanwhile one of Auckland's largest gay pride festivals has been canned this year in light of the rapidly unfolding Omicron threat.
Today the organisers of the Big Gay Out announced they had taken the difficult decision to cancel the outdoor festival, saying the communication from the Prime Minister in recent days meant they had a duty to take a cautious approach to holding events given the health and safety of their communities lay at the heart of their work.
Cabinet will meet for the first time of the year today at 4pm to discuss an array of Covid-19 matters but the most anticipated will be the review of the current traffic light settings.
The outcome will be announced tomorrow as Labour MPs gather in New Plymouth for a New Year caucus get-together.
Northland is the only region to remain under red restrictions while the rest of the country is at orange.
Overnight it was announced that the upcoming MIQ room release was postponed as the Omicron variant loomed on New Zealand's doorstep.
In a statement, head of MIQ Chris Bunny said there had been a tenfold increase in positive Covid-19 cases at the border compared to December.
Yesterday, director general of health Dr Ashley Bloomfield indicated that more restrictions were likely to be put in place as the country prepared for the inevitable Omicron outbreak.
Bloomfield said Omicron was a "different beast" from Delta.
Working from home and lowering the number of people allowed at gatherings were all back on the table, but he said the health response wouldn't necessarily be around more lockdowns.
Meanwhile, health authorities are chasing up 10 people on a bus who had been deemed close contacts of the current MIQ Omicron case but were yet to be tested. It came as revelations of a household contact of the border worker had tested positive for Covid-19.
An investigation into how an Auckland MIQ worker became infected with Omicron is continuing as the Government moves to stamp out the virus before it sparks a summer outbreak.
The infected MIQ worker, who is based at Auckland's Stamford Plaza and is fully vaccinated, tested positive for Covid-19 last week during surveillance testing. It was later confirmed they had the Omicron variant.
The Health Ministry said an investigation into the transmission route and testing of staff from the facility continued.
