Updated project metadata. Although the COVID-19 pandemic has ended, it is important to understand the pathology of severe SARS-CoV-2 infection associated with respiratory failure and high mortality. In this study, a proteomics approach using nano-HPLC-MS/MS (QExactive HF) was used to compare the plasma proteome of COVID-19 survivors (COVID-19; n=10) and deceased individuals (CovDeath; n=10) with that of healthy individuals (Ctr; n=10). The effects of SARS-CoV-2 infection on the alteration of plasma proteins by lipid peroxidation products such as 4-hydroxynonenal (4-HNE), malondialdehyde (MDA) and 15-deoxy-12,14-prostaglandin J2 (15d-PGJ2) were also examined. The results suggest that the development of COVID-19 strongly alters the expression of proteins involved in the regulation of exocytosis and platelet degranulation. These changes were most pronounced in the CovDeath group. In addition, a significant increase in proteins modified with reactive aldehydes was observed in all patients. In the COVID-19 and CovDeath groups, the levels of 4-HNE adducts increased 2- and 3-fold, respectively, whereas MDA adducts increased 7- and 2.5-fold, respectively. Signaling kinases and proinflammatory proteins were particularly affected by these modifications, and the amount of 4-HNE modifications confirmed previous findings on the relevance of 4-HNE in disease pathogenesis and lethal outcome. Protein adducts with 15d-PGJ2 were increased 2.5-fold in COVID-19 patients, including modifications of proteins such as p53 and STAT3, whereas CovDeath showed a decrease of approximately 60% compared with Ctr. It can be assumed that the observed changes in protein expression and modification in COVID-19 are unlikely to be used as prognostic biomarkers because they are also present in the other inflammatory diseases. However, larger studies may prove that the extent and the nature of protein modifications in plasma may be a predictor of the course of SARS-CoV-2 infection.