Victoria reported eight new coronavirus cases on Thursday – including one in a protester who attended last weekend’s Black Lives Matter rally in the Melbourne CBD.

The state’s chief health officer, Brett Sutton, said the infected protester had developed symptoms after Saturday’s rally, which drew a crowd of tens of thousands.

“It would be very unlikely that it’s been acquired from the protest,” he said.

“Nonetheless, because of attendance at the protest within 24 hours of developing symptoms, they were potentially infectious.

“The lesson about warning people not to attend applies. The directions in place that limit mass gatherings of any size to 20 are for a reason.”

Professor Sutton said the infected protester, a man in his 30s, wore a mask to Saturday’s rally, as did many others.

But masks did not provide 100 per cent protection from the coronavirus.

Political leaders and public health officials have consistently advised against attending mass gatherings, such as demonstrations, during the coronavirus pandemic.

On Thursday, Prime Minister Scott Morrison said the weekend’s anti-racism rallies were a “real blocker” to further easing coronavirus restrictions.

Health Minister Greg Hunt later told Parliament that the country’s national panel of medical experts had met again on Thursday, and “emphasises the very high-risk environment” of mass demonstrations.

“The medical experts have been absolutely clear – there are not safe mass gatherings,” he said.

“Please do not go. Please do not endanger your fellow Australians.”

Tweet from @VicGovDHHS

Professor Sutton said he had been clear about the risks of attending the protests.

“The public health direction that I’ve laid out says that community gatherings shall not exceed 20,” he said.

“I don’t know I could have said it any more strongly … There are different areas in Australia with different epidemiology, which means the risk is maybe not so great if you were to gather in bigger numbers in the
Northern Territory … but for Victoria, I was entirely clear about the potential risk of transmission.”

The other cases reported on Thursday were: Two in hotel quarantine, one linked to the Rydges on Swanston cluster (which has 15 infections), one in a worker from a Bupa aged-care facility in suburban Clayton, one in a toddler from a Parkville childcare centre and two under investigation.

Despite the spike in infections, Professor Sutton said Victoria’s general coronavirus trend was still positive.

The state had fewer community cases than last week – but had now had “zero days with zero cases”.

Elsewhere, Queensland had one new COVID-19 case on Thursday, in a returned traveller.

NSW and Western Australia both had days without new confirmed infections.