The new cases are in Northland, Auckland, Bay of Plenty, Lakes, Waikato, Hawke's Bay and Wellington.
The border worker returned a positive result for Covid-19 late yesterday afternoon and are now in isolation, the Ministry of Health said in a statement this afternoon.
The test was taken as part of routine border worker surveillance testing. The New Zealand Herald understands the person worked at the Stamford Plaza Hotel.
It was confirmed by the Ministry this afternoon that the worker has Omicron - the highly-infectious strain of the virus that is spreading rapidly around the world.
"All of the case's seven household contacts identified have already been contacted, isolated and tested, and returned a negative result." the ministry said.
"A further 48 close contacts are in the process of being contacted, asked to isolate and get tested. Fifteen of these contacts have already returned a negative test result, including five contacts in Taupō.
Among the close contacts are 39 people who were on two bus trips with the case.
"The MIQ worker on the bus trips was wearing their mask throughout both journeys," officials said. "At this stage, exposure events have been identified at the MIQ facility, on bus travel to work and a small number of shops."
The ministry released a series of "high-risk" locations of interest linked to the worker. Those who are at the locations at these times are advised to get tested immediately, self-isolate and then get a further test on day 5 after exposure.
On Friday afternoon, the worker returned a positive result for a routine surveillance test taken on Wednesday afternoon, the Ministry said.
The worker was fully vaccinated, up to date with regular surveillance testing and has cooperated fully with health authorities in helping manage any risks.
Auckland health officials are working at pace to identify any further contacts and exposure events.
Whole genome sequencing has linked the MIQ worker to two returnees within the facility who travelled from India who arrived on January 8 and tested positive two days later.
The MIQ worker is deemed to have been infectious from January 10.
Auckland Regional Public Health are working with MIQ staff to look for any possible routes of transmission between the returnees and the MIQ worker. MIQ staff at this facility are in the process of having an additional test arranged.
Meanwhile, there are 43 new cases of Covid-19 detected at the border today.
Twenty-two people are in hospital with the virus, including two in intensive care.
It comes as the vaccine roll-out for 5 to 11-year-olds is set to begin tomorrow. It will be available for free at all the same places that provide the adult vaccine: parents will be able to access walk-in clinics, or use BookMyVaccine to use other health providers.
While there are no plans for a school-based immunisation programme, schools are being considered as community vaccination sites.
