LONG COVID AS A MULTISYSTEM DISORDER: A LITERATURE REVIEW ON PATHOPHYSIOLOGY, CLINICAL MANIFESTATIONS, AND GLOBAL BURDEN

Resumo

Introduction: Coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, represents one of the most widespread infectious pandemics in modern history, significantly burdening public and private healthcare systems. Beyond the acute phase, a substantial proportion of individuals develop persistent symptoms, a condition known as long COVID or post -acute sequelae of SARS -CoV-2 infection (PASC). According to the World Health Organization, long COVID is defined as symptoms that arise within three months of infection, persist for at lea st two months, and cannot be explained by alternative diagnoses. Objective: To analyze the epidemiology, clinical manifestations, pathophysiological mechanisms, and socioeconomic impact of long COVID as a multisystem disorder. Methods: This study is a narr ative review based on recent literature addressing long COVID. Data were gathered from observational studies, meta -analyses, and clinical reports focusing on prevalence, symptomatology, underlying mechanisms, and long- term outcomes associated with post-COVID-19 conditions. The searched databases were PUBMED and EMBASE. Results: The prevalence of long COVID varies widely, ranging from 4.7% to 80%, reflecting heterogeneity in study designs and populations. Approximately 22 -38% of individuals report at least one symptom 12 weeks after infection, while 12 -17% present with three or more symptoms. Clinical manifestations are multisystemic, including fatigue, dyspnea, chest pain, palpitations, cognitive impairment, autonomic dysfunction, musculoskeletal pain, gast rointestinal disturbances, and neuropsychiatric symptoms. Notably, long COVID can affect individuals regardless of age, initial disease severity, or symptomatic status during the acute phase. Pathophysiological mechanisms involve persistent inflammation, i mmune dysregulation, endothelial dysfunction, mitochondrial impairment, and possible viral persistence. Severe acute complications, such as acute respiratory distress syndrome (ARDS), may contribute to long -term sequelae, including reduced pulmonary functi on, decreased exercise capacity, and chronic dysfunction of cardiovascular, renal, and neurological systems. Longitudinal evidence suggests that these effects may persist for years, increasing the risk of chronic diseases. Additionally, long COVID imposes a substantial socioeconomic burden, including reduced functional capacity, increased prevalence of anxiety and depression, and decreased workforce productivity. Conclusion: Long COVID is a complex and multifactorial multisystem condition with significant clinical and economic implications. A better understanding of its mechanisms, along with standardized diagnostic criteria and targeted therapeutic strategies, is essential to reduce its long - term global burden.