UPDATED: It may be impossible to trace all the close contacts of a protester who tested positive for coronavirus after attending Melbourne's Black Lives Matter protest, Victoria's top health official says.
The man, in his 30s, wore a mask to the protest last Saturday but developed symptoms in the 24 hours after the rally, Chief Health Officer Brett Sutton said on Thursday.
He is the first protester confirmed to have COVID-19 after the demonstration, which was attended by thousands of people.
Professor Sutton said it was unlikely the man contracted the virus at the protest but may have been infectious. It was not known if he had the COVIDSafe app downloaded or whether it was activated.
If he didn’t, and the man spent an extended time near strangers, Professor Sutton said the department may not be able track down all his close contacts.
"If there are people around you, but you can’t identify them, then they are impossible to identify," he said.