The Ministry of Health has confirmed an open home was held at a Papatoetoe address when a tenant deemed a "casual-plus contact" was there.
The open home was on Saturday.
The tenant was in their room at the time of the viewing, the Spinoff have confirmed.
"The tenant later developed symptoms and tested positive for Covid-19, and is among those reported in recent days."
A house viewing advertised for Sunday, was cancelled, the real estate agent telling possible visitors a member of the household "had come down with the flu".
The real estate agent confirmed to the Spinoff they were aware of the situation, but could not comment further because of an "agreement with the health ministry to not disclose any information".
They declined to say if they were aware the tenants were under instructions to self-isolate.
At the time of the viewing, Auckland was at alert level 2 and the rest of the country was at alert level 1.
The house address has not been listed on the ministry's locations of interest as everyone who visited was identified.
At today's 1pm press release the ministry confirmed the viewing "at the residence of the family (Cases I, J, K)".
It said the viewing lasted 30 minutes and three people attended.
The agent and the viewers were contacted by public health officials on Tuesday.
They have been tested and are awaiting results.
There are no new community cases of Covid but there are three new cases in managed isolation.
One of the three is historical and not regarded as infectious.