The COVID-19 pandemic, induced by the SARS-CoV-2 virus, has had a profound global impact since its inception in late 2019, bringing forth unparalleled challenges in public health and medical research. A significant concern remains the potentially severe lung injuries induced by the virus, with complications ranging from acute respiratory distress syndrome (ARDS) to persistent symptoms in «Long COVID.» This comprehensive review aims to explore the intricacies of lung injuries resulting from COVID-19 and the implications and risks of re-exposure, especially amidst the evolving landscape of SARS-CoV-2 variants. Drawing from peer-reviewed articles, case studies, and meta-analyses published from December 2019 to September 2023, the review delineates the complex dynamics between pre-existing respiratory conditions and COVID-19 outcomes. The early phases of the infection are characterized by severe afflictions to the respiratory system, including pneumonia and ARDS. A substantial fraction of patients experience persistent symptoms known as «Long COVID,» where the lungs continue to show signs of inflammation and reduced functional capacity. The central facet of this exploration hinges on understanding the implications of re-exposure to the virus, with a keen focus on the potentially exacerbated impact on previously damaged lung tissues and the influence of vaccination in modulating clinical outcomes upon re-exposure. The immune responses showcase a rich tapestry of cellular engagements, from innate to adaptive immune responses. The discussion broadens to encompass the serious repercussions of newer variants, including Delta and Omicron, on re-exposure dynamics, underscoring the necessity for an adaptive healthcare approach responsive to variant-specific clinical manifestations. Furthermore, it explores the wide range of severe complications stemming from re-exposure, emphasizing the critical role of vaccination in potentially reducing the severity of pathophysiological outcomes. The review brings to the forefront the urgent need for continuous surveillance and adaptive healthcare strategies in light of the complexity introduced by evolving variants, encouraging further research in this pivotal area of study. It seeks to offer a deep insight into lung injuries and re-exposure risks, providing a rich resource for healthcare professionals and guiding future investigative efforts in this domain.
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