 The persistence of symptoms long after acute SARS, COVID-2 infection is a concern, referred to as long COVID or post-COVID-19 condition by the World Health Organization, WHO. Despite studies suggesting that long COVID can manifest regardless of initial illness severity, the underlying pathophysiology remains unclear. A comprehensive review was conducted on 11 bibliographic databases and included 98 articles, with 54 focusing on hypotheses on pathophysiology involving COVID patients. Studies displayed heterogeneity in terms of initial illness severity, timing of analysis, or presence of a control group. The main underlying mechanisms proposed so far include autonomic nervous system damage, immune dysregulation, autoimmunity, endothelial dysfunction, occult viral persistence, and coagulation activation. Evidence on why persistent symptoms occur is limited, with existing studies involving long COVID patients being highly heterogeneous. This article was authored by D. Castanari Zapatiro, P. Shallan, L. Cone, and others. We are article.tv, links in the description below.