The role of hydrogen bonding is relevant for both interaction and structural pinning of a ligand to a target protein. Biochemically, the availability of hydrogen bonding of a ligand can influence the transport of the small molecule through the bloodstream and barrier penetration though membranes, and permeability in different media . In this section a comparison of the hydrogen bond contacts of Nirmatrelvir, Molecules 48:32 and 74:19 to Mpro. There is significant overlap in the set of hydrogen bonds. Individually the hydrogen bond information can be found in the gold docked mol2 files available in the figures directory of the supplementary information download.