Meghan O'Rourke says long COVID and other chronic illnesses put an unwieldy burden on patients, who have to testify to the reality of their own illness. Her new book, The Invisible Kingdom, chronicles her personal struggle to find diagnoses for her own nerve pain, brain fog, extreme fatigue and other symptoms."When you're at the edge of medical knowledge, the lack of evidence is treated as evidence that the problem is you and your mind," O'Rourke says. "I felt, in a sense, kind of locked away in a room like a 19th-century hysteric."