A health expert has called on the New South Wales government to follow Melbourne’s lead in making face masks mandatory.

Residents of Melbourne and the Mitchell Shire are required to wear face coverings starting Thursday. Those failing to comply risk a $200 fine.

Mary-Louise McLaws, an epidemiologist and World Health Organization (WHO) adviser, said a similar order should be applied across Sydney “within days” to contain the coronavirus outbreak in NSW.

“I know this will be criticised because it’s across a wide geographical area, but that’s the point,” Professor McLaws told the ABC.

She said new evidence showed wearing “any sort of cloth is better than a bare face” to contain the virus spread.

“Some of the new studies show that some three-layered fabrics give you up to 70 per cent protection,” she said.

“So if everybody is wearing them, that’s doubling your effectiveness really.”

On Monday, NSW Premier Gladys Berejiklian urged the people of the state to wear a mask “if you cannot guarantee people around you will respect that social distancing”.

Federal Deputy Chief Medical Officer Dr Nick Coatsworth said mask use is encouraged for residents in hotspot areas.

“What we hope and are confident of is that these outbreaks in NSW will be brought under control and we won’t have to move to a policy of mandatory mask usage anytime soon,” Dr Coatsworth told Sunrise.

He also told the ABC: “Mandating mask use … sounds like a very easy and straightforward policy to implement, but if you mandate something, you have to enforce it, you have to give people fines, you have to ensure that the supply of masks is adequate.

“We want Australians to be absolutely clear that their primary mechanism of defence against COVID-19 is distance – physical distance, getting themselves tested when they’re unwell and supporting our contact tracers.”

This article originally appeared on Over60.