ATP5MK and infectious disease: A comparison of the obtained AGP concentration values between the three analyzed study groups clearly shows that AGP concentration values significantly increase during the course of inflammation accompanying severe COVID-19, and after its resolution (the group of recovered patients) they decrease to values considered physiological, which is consistent with previous reports on the role of AGP in the development of inflammation associated with the course of many inflammatory diseases, including infectious diseases [11,12,13,14].