New Zealand Rugby's headquarters in Wellington is in lockdown after an employee presented with concerning symptoms.
It's understood the person is being tested for Covid-19.
No one is allowed in the office and employees have been told to work from home. But other businesses and groups are continuing to work in the building and are unaffected by the news.
NZ Rugby spokeswoman Tracey Kai said the organisation made the call late last night after being notified by staff about the person with symptoms.
"At this stage nothing is confirmed we are just taking precautions... it may just be nothing but until we really know for sure we're just following Ministry of Health guidelines.
Kai said staff were scheduled to work from home tomorrow anyway as a trial.
A media stand-up with Rugby New Zealand CEO Mark Robinson was scheduled to take place at the organisation's headquarters this morning, but was moved to a phone call conference at the last minute.
Usyk won the fight by unanimous decision, with all three judges scoring it 116-112.