The main topic for debate during Sunday’s face-off between former Vice President Joe Biden and Vermont Sen. Bernie Sanders was the coronavirus pandemic sweeping through the United States. And the theme was clear. According to both 2020 Democratic presidential candidates, President Donald Trump was not doing a good enough job of handling the crisis. But Biden could not make it out of his first answer of the debate without breaking one of the Centers for Disease Control and Prevention’s hygiene guidelines for protecting others from the spread of the virus. “What do you say to the American people who are...