Expert who has never caught Covid tells Aussies to wear face masks every time they leave the house - amid fresh mandate in one state

A leading epidemiologist who has never caught Covid-19 has advised Australians to wear face masks every time they leave the house to avoid catching the virus. 

The warning from University of Western Australia epidemiologist Zoe Hyde comes as the same state reintroduced face mask rules at Perth public hospitals on Monday. 

'It's a very simple principle. If you don't breathe the virus in you're not going to get sick,' Dr Hyde told WA Today. 

She also said the currently available Covid-19 vaccinations are 'out of date' and the government should speed up the process of rolling out new updated vaccines 'because they will offer much better protection from infection'. 

A recent surge in Covid-19 cases - Australia's eighth wave of the virus - prompted the Western Australian government to reintroduce surgical mask wearing in high-risk clinical areas of public hospitals. 

These include wards where vulnerable patients are being treated and intensive care, haematology, oncology, organ transplant and renal dialysis units. 

'We need to do what we can to make sure we're keeping each other safe - especially our most vulnerable,' WA Premier Roger Cook said.

'It's a simple measure that will reduce the spread of Covid-19 and help keep our most vulnerable safe.'

Mr Cook, who contracted Covid-19 earlier in November following a trip to Japan,  said it was important to take care.

'This is an expected part of the ongoing evolution of Covid-19 in the community, as people's immunity wanes over time,' he said.

'My advice remains the same – stay home if you are sick, wash or sanitise your hands regularly and cover your mouth when you cough. 

'Do not visit high-risk settings such as aged-care facilities or hospitals if you have cold or flu symptoms.'

'It's an expected part of the ongoing evolution of Covid-19 in the community as people's immunity wanes over time,' he said. 

WA's Chief Health Officer Dr Andy Robertson said Covid-19 cases had been increasing since early September.

'Given the increase in Covid-19 hospitalisations and health staff off sick, health service providers have agreed on consistent mask recommendations across our public health system.'

Surgical masks will also be recommended for staff and visitors in all public hospital clinical areas.

Dr Robertson said private hospitals and aged care facilities should also consider bolstering their mask-wearing rules for staff and visitors.

'Covid-19 is very much still with us and my advice for the community remains the same - stay home if you are sick and do not visit high-risk settings such as aged care facilities and hospitals if you have cold or flu symptoms,' he said.

Dr Hyde, though, said governments had become complacent about the dangers of the virus.

'There's this hope that Covid-19 is sort of just going to turn into something like a common cold, and we're just going to have one Covid-19 season per year. Clearly that's not what's happened,' she said. 

Former Australian deputy chief health officer Dr Nick Coatsworth claimed reinstating mask mandates would have little impact.

'That's not going to make any difference at the moment,' Dr Coatsworth told 2GB on Friday.

'If you say 'Look, wear masks in some situations but not others, don't socially distance and go about your business', then all the masks are doing is polluting the environment.'

'We need to be smarter about how we manage this.