Severe acute respiratory syndrome coronavirus 2 causes lung inflammation and injury

BACKGROUND: As of 14 October 2021, coronavirus disease 2019 (COVID-19) has affected more than 246 million individuals and caused more than 4.9 million deaths worldwide. COVID-19 has caused significant damage to the health, economy and lives of people worldwide. Although severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is not as lethal as SARS coronavirus or Middle East respiratory syndrome coronavirus, its high transmissibility has had disastrous consequences for public health and health-care systems worldwide given the lack of effective treatment at present. OBJECTIVES: To clarify the mechanisms by which SARS-CoV-2 caused lung inflammation and injury, from the molecular mechanism to lung damage and tissue repair, from research to clinical practice, and then presented clinical requirements. SOURCES: References for this review were identified through searches ‘(COVID-19 [Title]) OR (SARS-CoV-2 [Title])’ on PubMed, and focused on the pathological damage and clinical practice of COVID-19. CONTENT: We comprehensively reviewed the process of lung inflammation and injury during SARS-CoV-2 infection, including pyroptosis of alveolar epithelial cells, cytokine storm and thrombotic inflammatory mechanisms. IMPLICATIONS: This review describes SARS-CoV-2 in comparison to SARS and explores why most people have mild inflammatory responses, even asymptomatic infections, and only a few develop severe disease. It suggests that future therapeutic strategies may be targeted antiviral therapy, the pathogenic pathways in the lung inflammatory response, and enhancing repair and regeneration in lung injury.