F2 and susceptibility to pneumonia measurement: Examining the concentrations of the different antibody subtypes, it was observed that the greater the severity of pneumonia, according to the CURB-65 scale, the more elevated the concentration of all types of IgA aPL, the statistical significances being p = 0.026 for IgA anti-CL, p = 0.005 for IgA anti-β2GPI and p = 0.009 for IgA anti-PS/anti-PT.