In late February, at the early stage of the U.S. outbreak, Surgeon General Dr. Jerome Adams implored Americans not to stockpile masks, saying they are not effective in preventing the general public from catching the disease and need to be saved for healthcare workers on the front lines. Along with the U.S. Centers for Disease Control and Prevention (CDC), Adams encouraged the public to instead wash their hands often and thoroughly. In March, 88% of Americans said hand-washing is more effective than wearing surgical masks, with most of the rest (11%) saying they were equally effective.

But on April 3, the CDC reversed course on its face mask guidelines, following growing evidence that presymptomatic and asymptomatic carriers could transmit the virus more readily than previously thought. The new recommendation called for the use of masks or cloth face coverings for Americans when they are in public and unable to follow social distancing guidelines in order to prevent the spread to others, including from unknowingly infected carriers.