Why use a mask? Because it's a game of statistics. R0 of this virus is extremely high (above 2). Everything that reduces R0 helps. Social distancing, (Hand) sanitation, Mask use by infectious, Mask use by everyone else, etc. It all pushes the locally observed R0 value down.
— Tobi Lutke 🌳🌲🛒🕹 (@tobi) April 1, 2020
