Health officials are awaiting the results of more tests to piece together when and how the latest Covid-19 case got the virus.
The person tested positive on their fifth day of self-isolation at home in Hamilton, after returning three negative tests during their 14 days' managed isolation at Auckland's Pullman Hotel.
It is the fifth case to be linked to the hotel and investigations are continuing.
Since late January, everyone who has completed managed isolation at the Pullman has been required to self-isolate at home for a further five days and be re-tested.
It is not yet known whether the person has one of the more infectious variants of the virus, or whether the infection is linked to the earlier cases.
Yesterday, Director of Public Health Caroline McElnay said genome sequencing would provide further information about that.
She said there was still a chance it could be a historical infection.
More details would be released as soon as they were available, McElnay said.
Health officials have emphasised that the public health risk from the latest case is low, because they have been in self-isolation at home.
Both of the person's close contacts have tested negative.
Pullman empties out
The last 60 returnees at Auckland's Pullman Hotel are due to depart today, having completed their 14 days' managed isolation.
The hotel has not been accepting any new arrivals, as investigations continue into the Covid-19 cases linked to the facility.
All of those departing will still need to self-isolate at home for five days and be re-tested.
With the hotel empty, it will undergo a deep clean and more work will be done to try and work out how people became infected there.
The investigation into how the transmission occurred is inconclusive at this stage, McElnay said.
With no guests, McElnay said it would also be an opportunity to make changes and improvements to the hotel, if it is to be used again for managed isolation.
National wants 'common sense' changes to MIQ
National's Covid-19 response spokesman Chris Bishop said the string of cases must prompt changes to the managed isolation system.
He said overall the system had been successful, but things could be done better.
That should include separating arrivals from high-risk and low-risk countries, with those in the former group going into dedicated facilities.
Bishop said this was important given the emergence of the more infectious variants of the virus.