A person with Covid-19 who was originally thought to be linked to the South Auckland cluster is again under investigation.

A Westfield St Lukes store employee, the person worked at the mall for a number of days while infectious with Covid-19, health officials say.

But because of level 3 restrictions, there was limited contact with members of the public, Auckland Regional Public Health Services (ARPHS) says.

"There is a very small possibility that members of the public may have been exposed to the virus from 10.30 to noon on Wednesday 12 August, before the majority of shops closed for alert level 3,"ARPHS said in a statement.

"This person visited the Countdown for 10 minutes at around 11.15 am on this morning."

One of six new positive cases announced yesterday, the person now been reclassified as "under investigation with a link still to be firmly established," director general of health Dr Ashley Bloomfield said today.

Close contacts of the employee have been identified and are in self isolation.

The employee was also at the mall on the afternoon of August 12, and on August 14, 15 and 17 under level 3 restrictions, but there was no interaction with members of the public, ARPHS said.

People who visited the mall on these days are considered "casual contacts" and do not need to self isolate.

But they should keep an eye out for symptoms of Covid-19, such as a new or worsening cough, sore throat, runny nose, loss of sense or smell, or fever, and call their GP or Healthline if they fall ill.

The St Lukes store was one of two supermarkets hastily closed for deep cleaning yesterday, after health authorities alerted management that two separate shoppers who had tested positive for the virus had visited the stores.

Countdown's general manager for health and safety Kiri Hannifin said two people infected with the virus had shopped at the Auckland CBD Countdown on Quay St and the Westfield St Lukes Mall Countdown last week.

The Auckland District Health Board had advised them at midday on Wednesday about the people's movements, but noted the shopping trips were deemed low risk and casual contact exposures were minimal, she said.

Hannifan said while they had not been asked to close or clean the stores, it was something the company was doing as an extra precaution.

This morning, a Countdown spokesperson said both stores reopened early yesterday evening after an extensive clean.

There are now two people with Covid-19 who are not clearly linked to the South Auckland cluster, which today numbered 80 people.

The other person, a maintenance worker from Rydges Hotel who tested positive but who is not related to the broader Auckland cluster, used the same lift shortly after a Covid-positive woman from the United States, Bloomfield said today.

It was a matter of minutes between the maintenance worker and the Covid-positive woman being in the lift and was a "strong line" of investigation.

Bloomfield said it could be that the maintenance worker was infected by touching the same button as the Covid-positive returnee.

While there is usually low risk of contamination from touching an infected surface, the pair's close proximity meant there was a good chance that could be how the infection occurred, he clarified later in the update.

The two nurses who went into the woman's room have both now returned negative test results.

Five new confirmed cases of Covid-19 were announced today, all related to the community cluster in Auckland.

Four are in Auckland and the fifth is related to the Tokoroa case.

There are six people in hospital: one in Auckland City Hospital, four in Middlemore, one in Waikato, and one person is in Middlemore in a stable condition at the intensive care unit.