For nearly four decades, Dr. Anthony Fauci has been leading the fight against infectious diseases in America - including AIDS and COVID-19. Now, he's stepping away.Earlier this week, Dr. Fauci announced he would retire as the head of the National Institute of Allergy and Infectious Diseases at the end of the year. In this episode, we'll talk with Dr. Fauci about his decision to leave, and take a look at the twists and turns of his long - and sometimes controversial - career.In participating regions, you'll also hear a local news segment to help you make sense of what's going on in your community.Email us at considerthis@npr.org.