It could be possible to hypothesize that belatedly, the neutralization of the virus by the immune response [34] and the reduction in endothelial dysfunction could progressively increase the availability of cGMP by means of both increased production of NO [32] by endothelial cells and decreased inactivation by PDE5 with the use of sildenafil, progressively helping to compensate for the vascular tone imbalance, which could explain the relative tendency toward improved oxygenation parameters in the latest measurements in Fig. 3. This evidence concerns the gene PDE5A and endothelial dysfunction.