Mouth-muffle

Nowadays we’re having trouble with a very new and very dangerous virus, even kill people, I don’t know what the English name of it. This virus causes pneumonia. The sure thing is it’s a kind of contagion and infected by person to person, but don’t know what the way is exactly, and how to control it effectively. So on the street, most people are wearing mouth-muffle to avoid to be influenced by it, even though nobody know if it’s a good way.