THE TIME HAS come to start covering your face. As we reported April 3, the US Centers for Disease Control and Prevention now recommends all citizens voluntarily wear a cloth face mask for essential trips out of the house to the grocery store, doctor, or other public places where the 6-foot social distancing rules may be difficult to maintain. In short, most places. Wearing a cloth mask might help protect people around you, if you happen to be infected with Covid-19 but do not have symptoms yet. (These are Covid-19’s typical symptoms.) Some individuals infected with Covid-19 never show symptoms or do not get very sick, especially if they are young. Basically, these masks mainly help others, not you—though if used properly, a cloth mask may help you avoid touching your face and infecting yourself while out of the house.