The SARS-CoV‑2 coronavirus has become a major global health concern. Infection with SARS-CoV‑2 has caused millions of deaths worldwide, and the case fatality rate has been found to be largely related to pre-existing clinical conditions. The main clinical manifestation of COVID‑19 is the presence of respiratory symptoms. Severe complications of COVID‑19 are most often observed in people with significant medical histories. The SARS-CoV‑2 virus primarily attacks the respiratory system, causing pneumonia and acute respiratory distress syndrome, which can lead to severe systemic inflammation, multiple organ dysfunction, and death, especially in patients with pre-existing comorbidities. A number of meta-analyses strongly suggest that comorbid respiratory diseases, including chronic obstructive pulmonary disease and interstitial lung diseases, are factors in the development of severe forms of COVID‑19, worsening patient outcomes and survival rates. Studies have shown an association between adverse outcomes of COVID‑19 and the expression level of the angiotensin-converting enzyme 2 (ACE2) in these patients. Regarding other respiratory system pathologies, such as bronchial asthma and cystic fibrosis, it is known that the main unfavorable factor is long-term immunosuppressive pharmacotherapy preceding infection. In this article, we highlight the main respiratory comorbidities to better understand the pathogenesis of COVID‑19.
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