The United States is experiencing an especially bad flu season this winter. So grab your hand sanitizer, because we’re taking on the topic with a look a smart thermometers, like the ones made by KinsaHealth. The company’s thermometers connect to an app to give users medical advice and to track the spread of fevers (and, by association, the flu). Donald G. McNeil Jr. is a health and science reporter at the New York Times and joined Marketplace Weekend to discuss flu tracking.