That same week, Robert Redfield, director of the Centers for Disease Control and Prevention (CDC), appeared before lawmakers. Asked if people should wear masks, he had a straightforward answer: "No."

 

Now he's not so sure. On Monday, Redfield said told NPR that the CDC was reviewing its guidelines and may recommend general mask use to guard against community infection. It's likely only a matter of time before other mask holdouts, most prominently the World Health Organization (WHO), follow suit.

 

Writing last month, Adrien Burch, an expert in microbiology at the University of California, Berkeley, noted that "despite hearing that face masks 'don't work,' you probably haven't seen any strong evidence to support that claim. That's because it doesn't exist."

 

In fact, there is evidence of the exact opposite: that masks help prevent viral infections like the current pandemic.