Newly obtained emails confirm that the Centers for Disease Control and Prevention (CDC) changed its definition for both “vaccine” and “vaccinated” because people were pointing out that definitions did not seem to apply to the COVID-19 vaccines. “The definition of vaccine we have posted is problematic and people are using it to claim the COVID-19 vaccine is not a vaccine based on our own definition,” Alycia Downs, a CDC official, wrote in an email on Aug. 25, 2021, to a colleague. The definition is located on a page called Immunization Basics. “Vaccine” was defined since at least 2011 by the...