"When I was around six years old, I woke up one morning and couldn’t get out of bed. My legs wouldn’t move. I was paralyzed from the waist down. This was during the polio era, in the early 1950s. My mother came in because I wasn’t ready for school. I remember the alarm in her eyes. In those days, doctors made house calls, and he entered my room carrying his black physician’s bag, sat on the edge of the bed, stuck a thermometer under my tongue, and checked my pulse. There was little else he could do. The terror of polio haunted children and parents everywhere. It was common to see young people in leg braces or wheelchairs; those imprisoned in iron lungs we only heard about. I was lucky. It wasn’t polio; it was possibly a severe allergic reaction to a tetanus shot I had had a few days before, caused by the tetanus antitoxin, which is harvested from horse blood. Horses were so important to the production of antibodies that many of the great pharmaceutical companies began as horse farms. It might also have been a dangerous disease called Guillain-Barré syndrome, an autoimmune disorder sometimes associated with infections such as influenza, Zika, and dengue fever—but so far not Covid-19. After a day or two, I could move my legs, but the memory was searing."