This review covers the published papers describing endothelial dysfunction pathogenesis and molecular mechanisms behind the effect of low-level laser therapy on regulation of the said pathogenesis. Herein, we present the current experience of using laser therapy to prevent development of endothelial dysfunction in the context of post-COVID-19 rehabilitation, as well as the accumulated data on the methods of combination of external or intravenous laser blood therapy and influence on the immunocompetent. We provide justification for practicing personalized approach at various stages of post-COVID-19 rehabilitation and treatment. The basis allowing greater efficacy of post-COVID-19 rehabilitation, including protocols making use of laser therapy, is the analysis of single-nucleotide polymorphisms of genes that determine adaptation processes, peculiarities of the immune response to infectious pathogens, predisposition to the development of respiratory distress syndrome, severe pneumonia, sepsis, multiple organ failure, development of endothelial dysfunction, thrombotic complications, the analysis that allows identification of patients running higher risk of critical conditions.