As you deck the halls and traverse afar this holiday season, taking precautions to protect yourself from a quartet of infectious diseases can lessen your odds of bringing an illness into the new year. Flu, COVID, respiratory syncytial virus (RSV), and norovirus are making their winter rounds nationwide, and you may have heard the term “quad-demic” pop up online or in conversation (the first three are sometimes called a “triple-demic”). While the unofficial term for the four maladies circulating in tandem evokes a sense of impending doom, the quadruple threat isn’t so different from respiratory virus seasons past. “All of...