Michael Osterholm wears a cloth mask when he goes outside. He supports their use and believes they may help slow the spread of tide of the coronavirus. But his organization, the Center for Infectious Disease Research and Policy at the University of Minnesota, or CIDRAP, has dealt with a deluge of hate mail recently from people who believe it doesn't believe in them enough. Some have even accused Osterholm and others of contributing to the "death of thousands of humans"—something he has a...