Officials claimed this afternoon the woman - aged in her 20s who works at A-Z Collections in High St in a role serving customers - tried to phone in sick to her job at an Auckland CBD store but ended up coming in and wearing a mask.
The situation has been criticised by Auckland Mayor Phil Goff, who says he is frustrated and disappointed by the incident.
It has led to a call for Auckland CBD employees to work from home tomorrow.
The woman became symptomatic on Monday, and was tested on Tuesday.
But despite receiving advice to isolate, she talked to her manager, and went to work on Wednesday, wearing a mask.
But the co-owner of the store - who would not give his name - told The New Zealand Herald tonight those claims were not true. And he has called in the lawyers.
"We never knew staff [member] was sick - she never said she had a test," he said.
"We never knew she felt unwell. We just want to tell the truth."
The man said he and his wife - who is the store's other co-owner - have now contacted their lawyer over the claims.
He also said they had been targeted by abusive messages to their cellphone and email account.
"We feel really unsafe," he said.
As well as threats, they had been sent messages telling them to "go back to China", while other messages included their home address.
Goff told NewstalkZB it was a big problem and the worst thing that could've happened.
He said Auckland could beat Covid again, but Aucklanders needed to follow the rules, and work collectively.
The mayor also told RNZ "it is not great news".
"The worst thing that happened in this case is the woman having been told to isolate, then told by a store manager to come into work. That is frankly unbelievable.
"I just can not understand that. It defies common sense. There is a lesson in that, and you think that is a lesson people didn't need to learn."
Covid Response Minister Chris Hipkins also weighed in, saying it was disappointing the woman's manager told her to go to work despite the advice for to her to stay home.
Earlier, Hipkins and Director of public health Caroline McElnay urged people who work in downtown Auckland to do their jobs from home if possible tomorrow.