The rest of the country has been at alert level 1 since Tuesday morning.
The Ministry of Health is still working to find out if a person previously had Covid-19 - or not, after a "weak positive" case returned a negative result Tuesday morning.
The person is a close contact of a returnee from India who tested negative twice in managed isolation - but then tested positive after returning home to Auckland.
LISTEN LIVE TO NEWSTALK ZB 7.35am: Ashley Bloomfield; 8.05am: Stuart Nash and Mark Mitchell
Director general of health Dr Ashley Bloomfield says 29 close contacts of the returnee on a charter flight from Christchurch, have been tested.
One of those people returned a positive test - but this was believed to be an old infection.
That person, who has had no symptoms of Covid-19 since arriving in New Zealand, was retested and returned a negative result on Tuesday morning. Serology testing was also being undertaken.
The Ministry of Health was investigating the case to confirm it was an historic infection, and whether it was already reported as a case in India.
"Meanwhile, a precautionary approach is being taken and the person has been transferred to the Auckland quarantine facility," the Ministry said in a statement.
"The remaining people on the flight are in the process of being contacted and will be tested as appropriate."
Bloomfield said test results came through from time to time that were historical cases of Covid-19.
In these instances, the test result comes back positive but with a high "cycle threshold", or CT value, and is deemed to be a "weak positive result".
Research showed these people were not infectious and didn't pose a risk of passing the virus to others, Bloomfield said.
Three people with Covid-19 remain in hospital: one each at Auckland City, Middlemore and North Shore hospitals. All three patients are in isolation on a general ward.
The total number of active cases now is 61 - of those, 29 are imported cases in MIQ facilities, and 32 are community cases.
Health authorities have identified 4003 close contacts in the Auckland cluster, of which 11 have not yet been contacted.
"The risk of Covid-19, although small, does remain," Bloomfield said yesterday.
People with symptoms of Covid-19 would still be the priority for testing, but workers who come into contact with Aucklanders travelling around the country, including hospitality and tourism staff, will also be tested - even if they don't have symptoms.
Mobile testing sites will be made available for increased testing as the school holidays begin on Friday, Bloomfield said.
