Last summer, at a hospital in England, a man in his 70s being treated for complications with cancer tested positive for covid-19. He had lymphoma, and the disease plus his drugs weakened his immune system, making him particularly susceptible to the virus. He wasn’t too bad off, considering, and was sent home. That was Day 1. This is the story of what the doctors witnessed, over the course of his illness: the evolution of covid-19 inside his body. Before their eyes, they get a hint of what might be to come in the pandemic.  This episode was reported by Molly Webster.  Special thanks to Ravindra Gupta, Jonathan Li. Support Radiolab by becoming a member today at Radiolab.org/donate.      Want to learn more about some of the covid case studies? Here are a couple papers to get you started:The “U.K. Paper”, co-authored by Ravi Gupta, one of our sources for the episode: https://www.nature.com/articles/s41586-021-03291-y A case study out of Boston, co-authored by Dr. Jonathan Li, one of our sources for the episode: https://www.nejm.org/doi/full/10.1056/NEJMc2031364 For more on immune suppression and covid-19, check out this amazing Scientific American article:  https://www.scientificamerican.com/article/covid-variants-may-arise-in-people-with-compromised-immune-systems/