Counterargument
What if long COVID symptoms are primarily vascular, neurological, or immune?
Long COVID has documented vascular, autonomic, and immune mechanisms. A gut-mediated framing may be incomplete or wrong for many patients.
Where it is valid
Cases with dominant cardiovascular, microvascular, or autoimmune features and no significant gut symptoms.
What it challenges
The HCM application of host-substrate framing to post-COVID gut dysfunction.
Host Capacity Model response
HCM is not a unified theory of long COVID. It applies only to the subset of post-viral cases with significant gut and metabolic features. Vascular, autonomic, and immune-dominant phenotypes are out of scope.
Unresolved questions
- How do gut, vascular, and immune mechanisms interact in mixed phenotypes?
- Is host-substrate framing useful adjunctively even in vascular-dominant cases?
Evidence that would resolve this
- Phenotype-stratified long-COVID cohorts with gut, vascular, and immune endpoints.