Long Covid is a real thing.  It is probably part of a larger syndrome.   So, what's a "syndrome".   A syndrome is a collection of symptoms and physical findings (physical exam or lab tests or XRays, etc) that we recognize as being related.  AIDS was a syndrome before we knew what caused it.  Long Covid is a collection of symptoms and findings which are seen in some patients after an initial Covid infection.  Some physicians believe that Long Covid is one example of a persistent viral inflammation syndrome.  PVIS, if you will.  Articles and references will be posted here.