Current status and future perspectives on the mechanistic and pathophysiological understanding of long COVID.

BACKGROUND: Viral and infectious illnesses can exert profound and enduring effects on population health and well-being. In the aftermath of SARS-CoV-2 infection, post-acute sequelae, collectively referred to as Long COVID, have emerged as a major global health challenge, affecting more than 400 million people and contributing to estimated annual economic costs exceeding 1 trillion. SCOPE OF THE REVIEW: Long COVID encompasses a wide and heterogeneous spectrum of debilitating symptoms, including cognitive dysfunction, sleep disturbances, severe fatigue, and post-exertional malaise. Despite its substantial burden, fundamental uncertainties remain regarding its underlying pathophysiology, the development of robust diagnostic criteria, and the identification of effective therapeutic options. KEY INSIGHTS: This review synthesises current evidence on the biological mechanisms thought to contribute to Long COVID, spanning immune dysregulation, viral persistence, autonomic dysfunction, microvascular pathology, and other emerging hypotheses. We examine advances and limitations in contemporary diagnostic approaches and critically appraise existing treatment strategies, highlighting inconsistencies and gaps that hinder clinical consensus. IMPLICATIONS: By integrating interdisciplinary insights, this review underscores the urgent need for mechanistic clarity, validated diagnostic frameworks, and rigorously evaluated treatment pathways. Addressing these gaps will be essential to developing effective, evidence-based management strategies and mitigating the long-term impact of Long COVID on global health.