I thought that was kind of the point. Appolonia was Michael being pulled between his heritage and the independent identity he was originally trying to form. Diminishing his relationship with Kay was really about diminishing that break from his family's path. Returning to her was a way of lying to himself.

I've been curious to find any long Covid studies that focus on measurable, physiological symptoms.

I don't necessarily doubt that it's a real issue, but pretty much all the larger scale studies I've seen on long Covid rely on self-reported symptoms that are fairly vague or general, and don't appear to have high quality (or any) attempt to control for hypervigilance among the convalescent groups.