Every year, the Centers for Disease Control and Prevention (CDC) and pharmaceutical companies mount an aggressive campaign in the mainstream media to persuade Americans to get their flu shots. Flu shots are big business: industry analysts estimate that within the next five years, the U.S. flu vaccine market will be worth almost $3 billion annually. And profit margins are growing as manufacturers increase price premiums for the newer four-strain vaccines. The U.S. expects to distribute roughly 166 million doses for the 2017-18 flu season, up from 146 million doses in the previous year. As pharmaceutical companies bombard American consumers with ubiquitous billboards, drugstore enticements and radio announcements to “get your flu shot now,” the CDC has advised the industry to…