The woman at the centre of a coronavirus scare at leading law firm Clayton Utz has now tested positive, only days after being cleared.

A second test on Monday - taken after the woman developed flu-like symptoms over the weekend - again sent the firm into crisis mode.

A Clayton Utz employee leaves the firm's Sydney CBD office on Thursday after a COVID-19 scare. Rhett Wyman

However, this time Clayton Utz was advised by the NSW Department of Health that it did not need to close down its offices in Sydney's CBD or send people home - the course it took last Thursday after the woman's husband alerted the firm to possible contact.

The senior staffer, who works in the catering section, explained that his wife had visited her grandmother in the days leading up to her death last week at an aged-care facility in Macquarie Park, in the city's north-west. She took a test after an autopsy of her grandmother revealed she had contracted the virus. The result came back negative on Friday.

The staffer notified Clayton Utz's management late on Monday night about the results of the second test.