Nine has closed off part of its Sydney headquarters in Willoughby after a Today studio guest was diagnosed with Covid-19.
The decision was made after it was revealed US actor Rita Wilson, who appeared as a guest earlier this week, had contracted the virus along with her husband Tom Hanks.
"Nine today has taken action in line with our crisis response plan around a visit to our studio by Ms Rita Wilson on Monday this week, for an appearance on Today Extra with David Campbell and Belinda Russell," a Nine spokesperson said.
"Our actions are in line with the guidelines set out by the Government and Health Authorities. Those who were in prolonged contact with Ms Wilson have been tested and are self-isolating for 14 days."
The premises are currently being thoroughly cleaned in all areas Wilson visited, and all employees have been encouraged to monitor their health and practise good hygiene.
"Tracy Grimshaw is not hosting ACA tonight as a precautionary measure since she had minor surgery last week. Karl Stefanovic will host in her place," the spokesperson said.
"Arrangements for hosts for Today Extra are still being confirmed."
Updated at 4:30pm AEDT on 12 March 2020.
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