Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) appeared in late 2019, spreading around the world as a highly contagious disease named COVID-19. Although vaccines have emerged, challenges around the world have remained the same, finding effective treatments for preventing infection as well as improving the recovery of people infected with the SARS-COV-2 virus. COVID-19 is manifested by a range of symptoms, from a mild clinical feature to life-threatening pneumonia and multiple organ failure. Immunoglobulins, like most plasma proteins, are glycoproteins whose protein backbone is co- and posttranslationally modified by binding of complex oligosaccharides - glycans. In addition to their structural role, glycans are known to play an important role in glycoprotein function itself. Changes in the glycosylation of IgG, one of the key molecules in the immune response, drastically alter its function and determine immunomodulatory activity. Also, it is known that microelements, such as zinc, copper, iron, magnesium, selenium, manganese, iodine, play a significant role in the functioning of the human immune system. Therefore, it can be expected that the status of micronutrients of individuals may affect resistance to infection and recovery from infection. The hypothesis of the suggested project is that glycosylation of serum proteins and microelements is different depending on the severity of the clinical feature in COVID-19 patients and based on the analysis of these biomolecules in the early stages of SARS-CoV-2 virus infection and/or monitoring time can predict the clinical outcome and potential therapeutic solution. The proposed project will therefore evaluate changes in the glycosylation of serum proteins and microelements in COVID-19 samples from patients collected at different time points during COVID-19 infection, depending on the severity of the clinical feature. Glycans of total serum proteins will be analysed by ultra-high-performance liquid chromatography (UHPLC) based on hydrophilic interactions while microelements will be analysed using inductively coupled plasma mass spectrometry (ICP-MS) and flame atomic absorption spectroscopy.