Well before the COVID-19 pandemic, there were plenty of questions about autoimmune diseases. The 80 or so that have been identified can affect nearly every part of the body with a bewildering variety of symptoms. The diseases can be difficult to diagnose, and it is unclear what causes them. The concept of a disorder that causes the immune system, which is designed to protect us from foreign invaders, to launch an attack on healthy organs and tissues is mysterious and frightening.

Chest pain after COVID-19 is among the concerning symptoms cardiologists are seeing, even as hospitalizations from the latest surge of COVID-19 cases recede.