The government is currently urging people to wear face masks inside crowded public venues such as supermarkets, with modelling showing the highly-contagious Omicron subvariants BA.4 and BA.5 could result in daily COVID-19 cases peaking to about 5000 by Tuesday.

The modelling by the University of Adelaide shows the transmission potential could reduce by about 10 per cent if everyone started wearing face masks inside public venues.

Despite encouraging people to wear face masks, Health Minister Chris Picton has stopped short of agreeing to reimpose a formal mandate, saying to do so the government would need to declare another state emergency.

It comes after parliament passed changes to the Public Health Act in May that ensured baseline COVID-19 restrictions could continue without the need for a major emergency declaration.

Chief public health officer Professor Nicola Spurrier on Wednesday said authorities weren’t yet at the stage where they would consider bringing back an emergency declaration.

People at the moment are just hearing that it’s not bad enough to have mask mandates

But University of South Australia epidemiologist Professor Adrian Esterman told InDaily that a mask mandate would “do a really good job at reducing transmission” and the government should consider changing the legislation so that it could reinforce the rule more easily.

“If they have to reintroduce legislation then so be it,” he said.

“I’m not a politician or a lawyer so I’ve got no idea what that would involve, but surely the public health is more important than worrying about legislation?

“At the moment, we’ve got our hospital system under incredible stress, we’ve got so many patients now with COVID-19 and the numbers are going up and up at the same time we’ve got a massive flu outbreak, massive ramping.”

South Australia yesterday reported 4761 new COVID-19 infections, up from 4408 on Wednesday.

There are 231 people with COVID-19 in hospital, including seven people in intensive care and one ventilated.

Esterman predicted at its peak, the number of people with COVID-19 in hospital could top 300 by August.

He was critical of the government’s approach to encouraging people to wear face masks, saying the message was not being heard.

“Having our chief public health officer simply saying: ‘You should wear face masks does nothing,” he said.

“You go to a supermarket now and nine tenths of people aren’t.

“Either you have a really big campaign explaining why face masks are so important, or you introduce legislation that mandates it.”

Australian Medical Association vice-president Dr Chris Moy said there was currently confusion and “mixed messaging” about the need to wear face masks.

“The problem with ruling out mandates is that what people are hearing is that it’s (the current COVID-19 wave) not serious enough,” he told InDaily

“People may not understand the situation with respect to the fact that it’s much harder now in South Australia because of the winding back of the emergency management provisions.

“Other states are in a different position.”

Picton told InDaily that a public health emergency or major state emergency could still be declared if there was a need, but there was “no advice or consideration of that at this time”.

He said SA Health had started advertising the wearing of face masks through social media and materials were also being produced for employers and public venues.

“I want to thank South Australians for listening to the message from SA Health encouraging people to wear masks again, particularly in indoor, crowded or poorly ventilated places,” he said.

“I encourage all South Australians to do their part to prevent the spread of COVID-19 by getting fully vaccinated, taking advantage of the winter dose now available to over 30s, and wearing masks in public indoor settings.”

Masks are still mandatory in high-risk settings such as hospitals and other health care services, pharmacies, disability and aged care services, public transport, and on planes.

Close contacts of positive COVID cases must also wear a mask when leaving their home.

The rise in infections is prompted by the emergence of the Omicron BA.4 and BA.5 subvariants, which have the same severity as the previous BA.1 and BA.2 mutations of the virus but are considered more infectious and better able to evade immunity from vaccines.

Latest genome sequencing, conducted last week, shows just under 55 per cent of test samples were BA.4 and BA.5 – up from 24 per cent the week before.