Cashiers and customers wearing face masks are seen at a supermarket in Jena, Germany, April 6, 2020. The eastern German city of Jena became the first in the country to make wearing a protective face mask mandatory in public areas, such as shops, on public transportation and in buildings with public access during the COVID-19 pandemic. (Photo by Kevin Voigt/Xinhua)

A woman wearing a face mask is seen at a shopping mall in Jena, Germany, April 6, 2020. The eastern German city of Jena became the first in the country to make wearing a protective face mask mandatory in public areas, such as shops, on public transportation and in buildings with public access during the COVID-19 pandemic. (Photo by Kevin Voigt/Xinhua)

People wearing face masks queue to pick up ordered goods at a Hornbach market in Jena, Germany, April 6, 2020. The eastern German city of Jena became the first in the country to make wearing a protective face mask mandatory in public areas, such as shops, on public transportation and in buildings with public access during the COVID-19 pandemic. (Photo by Kevin Voigt/Xinhua)

A woman wearing a face mask is seen at a supermarket in Jena, Germany, April 6, 2020 The eastern German city of Jena became the first in the country to make wearing a protective face mask mandatory in public areas, such as shops, on public transportation and in buildings with public access during the COVID-19 pandemic. (Photo by Kevin Voigt/Xinhua)

People wearing face masks queue to enter a shop in Jena, Germany, April 6, 2020. The eastern German city of Jena became the first in the country to make wearing a protective face mask mandatory in public areas, such as shops, on public transportation and in buildings with public access during the COVID-19 pandemic. (Photo by Kevin Voigt/Xinhua)

Policemen wearing face masks are seen inside a police vehicle in Jena, Germany, April 6, 2020. The eastern German city of Jena became the first in the country to make wearing a protective face mask mandatory in public areas, such as shops, on public transportation and in buildings with public access during the COVID-19 pandemic. (Photo by Kevin Voigt/Xinhua)