Five million Victorians are being encouraged to wear masks, and even make their own, to help curb the spread of the coronavirus in the state.

Deputy chief medical officer Nick Coatsworth recommends residents in metropolitan Melbourne and Mitchell shire, north of the city, wear masks when social distancing cannot be maintained.

All of Melbourne’s local government areas and the adjacent Mitchell shire are in a second lockdown until at least mid-August because of Victoria’s spiralling coronavirus outbreak.

“This means if you have to leave your home for any of those reasons for which it is permissible and you are likely to find yourself in a situation where you cannot maintain 1.5-metre distance, it is advisable to be covering your face with a mask,” Dr Coatsworth said in Canberra on Thursday.

Victoria’s chief health officer Brett Sutton told residents to be crafty and make their own face masks instead of buying them.

“I think people will need to make their own masks,” Professor Sutton said on Thursday afternoon, after the state recorded 165 new cases.

“I don’t think there should be a rush on buying single-use masks, for example, and some masks that are able to be purchased … aren’t necessarily good for rewashing and reuse over days and days.”

The state’s health department is working on providing information on how to make a basic mask that can be reused and rewashed for “Melburnians and beyond, use for several weeks to come”.

Medical experts are divided on the use of masks, with some saying they only provide a marginal benefit.

But Dr Alex Polyakov, the director of the Master of Infectious Diseases Intelligence program at UNSW Sydney, wants their use to be much more widespread.

“I think mask use should be mandatory in Melbourne, particularly in high transmission areas and suburbs, and public and crowded places,” he said.

Hassan Vally, an associate professor in Epidemiology at La Trobe University, also thinks more people should wear masks.

“I do feel we need to get to a stage where the wearing of masks is more normalised in our society,” he said.

“We need to understand that anything we do to prevent transmission of the virus is useful and a mask is another barrier to infection that can be adopted, in addition to social distancing and hand hygiene, to help us get on top of disease spread.”

-AAP