Long COVID or post-COVID-19 syndrome first gained widespread recognition among 
social support groups and later in scientific and medical communities. This 
illness is poorly understood as it affects COVID-19 survivors at all levels of 
disease severity, even younger adults, children, and those not hospitalized. 
While the precise definition of long COVID may be lacking, the most common 
symptoms reported in many studies are fatigue and dyspnoea that last for months 
after acute COVID-19. Other persistent symptoms may include cognitive and mental 
impairments, chest and joint pains, palpitations, myalgia, smell and taste 
dysfunctions, cough, headache, and gastrointestinal and cardiac issues. 
Presently, there is limited literature discussing the possible pathophysiology, 
risk factors, and treatments in long COVID, which the current review aims to 
address. In brief, long COVID may be driven by long-term tissue damage (e.g. 
lung, brain, and heart) and pathological inflammation (e.g. from viral 
persistence, immune dysregulation, and autoimmunity). The associated risk 
factors may include female sex, more than five early symptoms, early dyspnoea, 
prior psychiatric disorders, and specific biomarkers (e.g. D-dimer, CRP, and 
lymphocyte count), although more research is required to substantiate such risk 
factors. While preliminary evidence suggests that personalized rehabilitation 
training may help certain long COVID cases, therapeutic drugs repurposed from 
other similar conditions, such as myalgic encephalomyelitis or chronic fatigue 
syndrome, postural orthostatic tachycardia syndrome, and mast cell activation 
syndrome, also hold potential. In sum, this review hopes to provide the current 
understanding of what is known about long COVID.