Long COVID: a review of mechanisms and treatment modalities

Abstract

Long COVID is defined by the World Health Organisation (WHO) as a condition arising within 3 months of an acute COVID infection with symptoms lasting for a minimum of 2 weeks. However, this syndrome is poorly understood and has been recorded to include many systemic manifestations, including neurological, respiratory, cardiovascular, gastrointestinal, dermatological, psychosocial, and metabolic systems. Constitutional symptoms also include fatigue, insomnia, body weight changes, poor attention span, hair loss, sexual dysfunction, myalgia, and joint pain, with fatigue being the most common. Given the various proposed mechanisms published in the literature, the postulated mechanisms and pathways are discussed in this paper to contribute to the understanding of defining this syndrome. In this review article, the authors first explored how endothelial damage from COVID infection can lead to a hypercoagulable state. In addition, the effects of an insufficient initial immune response can lead to viral persistence alongside a potentially prolonged hyperactive immune response that includes a cytokine storm and mast cell activation syndrome. Furthermore, the viral persistence can be exacerbated by antibody-dependent enhancement or complicated by molecular mimicry. Current pharmacological therapies are explored and evaluated to investigate their efficacy in addressing this complex and chronic presentation. This review article has been written after an extensive literature review to increase the understanding and awareness regarding Long COVID, as a sincere effort to direct further research for an effective diagnosis and management.