People wearing face masks shop at a grocery store in Vancouver, Canada, May 11, 2020. (Photo by Liang Sen/Xinhua)

A sign reminding customers to wear face masks is seen outside a grocery store in Vancouver, Canada, May 11, 2020. (Photo by Liang Sen/Xinhua)

Cashiers wearing face masks serve customers at a grocery store in Vancouver, Canada, May 11, 2020. (Photo by Liang Sen/Xinhua)

A man wearing a face mask shops at a grocery store in Vancouver, Canada, May 11, 2020. (Photo by Liang Sen/Xinhua)

A woman wearing a face mask shops at a grocery store in Vancouver, Canada, May 11, 2020. (Photo by Liang Sen/Xinhua)

A woman wearing a face mask shops at a grocery store in Vancouver, Canada, May 11, 2020. (Photo by Liang Sen/Xinhua)