On March 11, 2020, the World Health Organization named Covid-19 a pandemic, and public health around the globe changed forever.  Countries shut down their borders, businesses closed and furloughed workers, and millions of students went to remote learning. Two years in, more than one million Americans lost their lives. This week on Well, Now we mark this grim anniversary by talking about what we have and haven’t learned about this world-changing virus with one of the epidemiologists who first began sounding the alarm about Covid-19: Dr. Eric Feigl-Ding. Podcast production by Vic Whitley-Berry with editorial oversight by Alicia Montgomery. Send your comments and recommendations on what to cover to wellnow@slate.com. Learn more about your ad choices. Visit megaphone.fm/adchoices