A neighbour of a student with Covid-19 has returned a "weak positive" test result, as the Ministry of Health stands by comments slammed as categorically false by the student's workplace.

Three positive cases were announced yesterday, all international arrivals in managed isolation, after 5400 tests were done in a single day in Auckland alone.

However, the ministry also announced a person living in a neighbouring Vincent St apartment to the AUT student with Covid-19 had returned a "weak positive" result.

They were already identified as a close contact and in the Jet Park quarantine facility, the ministry said in a statement.

A weak positive result means a very small amount of virus is in the sample, which can mean a person was tested towards the end of the illness. Covid testing is not 100 per cent accurate.

"The individual's initial test result was negative, but a subsequent test has returned a weak positive result. A further test is now being taken. They are currently regarded as a case under investigation," the ministry said.

"Auckland Regional Public Health [ARPH] had already done some initial scoping of this case and will now be doing more detailed work on tracking and tracing any outstanding close contacts."

There was no update on investigations into how exactly the student was infected. They became symptomatic on Monday November 9, and their test returned positive on Thursday, which caused Auckland's CBD to go into a quasi-lockdown on Friday.

Fears lessened after genomic testing linked her infection to a Defence Force serviceman who caught the virus in the Jet Park facility. The serviceman ate at a cafe just 82m from the A-Z Collections store, where the student worked as a shop assistant.

That workplace came under fire after director of public health Dr Caroline McElnay on Thursday said the student called in sick after being tested, but ended up working after talking to her manager.

A-Z Collections owners later issued a statement via their lawyers, Focus Law, saying their employee never told them she was sick, sought to call in sick, or said that she'd had a Covid test.

That version of events was backed by a statement by the student, also released by Focus Law, and which claimed language barrier issues meant ARPH staff "made many errors in recording my previous whereabouts, actions and contacts".

The A-Z Collections store on High St. Photo / Dean Purcell

The Herald on Sunday has been unable to speak to the student. The ministry stood by the information "as being an accurate reflection of the information it was provided", a spokesperson said.

"The ministry works quickly on the basis of information available at the time which public health services work to verify independently where that is possible.

"The latest information does not affect in any substantive way the public health actions being taken and the ministry will not be commenting further on it."

ARPHS had confirmed "a Chinese-speaking nurse sat in on the interviews and offered to interpret, but that the case opted to speak in English", the ministry spokesperson said.

Meanwhile, masks will be made mandatory on planes and on public transport in Auckland, through a public health order to be presented to Cabinet tomorrow. The order could be in place by Thursday.

Despite the latest Covid scare preparations for a travel bubble with the Cook Islands are progressing, with NZ officials landing there yesterday.

Prime Minister Jacinda Ardern has been reluctant to give any time frame, but has said if it gets the green light borders could open within weeks.