Background & Aims: Coronavirus disease - 2019 (COVID-19) is a major pandemic that causes high morbidity and mortality rates. Aim of this study: to detect the relations between many risk factors, ACE-2, MCP-1, Micro RNA 146 gene expression, and COVID-19 infection and disease severity. Methods: This study was carried out on 165 cases of COVID-19 and 138 controls. ACE2 and MCP1 levels were measured in COVID-19 cases and control by ELISA and micro-RNA-146 expression by PCR. Results: We found an increased blood level of ACE2 and MCP1 in COVID- 19 patients than in healthy persons and a significant down-regulation of micro-RNA 146 gene expression in cases than in controls. There was a significant correlation between increased blood level of ACE2, regulation of micro-RNA 146 gene expression and severity of lung affection, a significant correlation was found between increased blood level of MCP1 and thrombosis in COVID-19 patients. Neurological complications were significantly correlated with more viral load, more ACE2 blood level, and down regulation of micro RNA146 expression. Conclusion: High viral load, increased blood level of ACE2, and down-regulation of micro-RNA 146 expression are associated with more severe lung injury and the presence of neurologic complications like convulsions and coma in COVID-19 Egyptian patients.