It’s like clockwork: first comes a brisk fall breeze, then comes the public health push to get a flu shot. But the U.S. Centers for Disease Control and Prevention’s messaging this year might look a little different from previous vaccination seasons. The agency has launched a messaging campaign dubbed “Wild to Mild” that uses adorable critters to illustrate how a vaccine can tame a bout with the flu by reducing its strength from that of an elephant or a lion to that of a mouse or a kitten.The framing might come as a surprise to those used to a blunter...