Protein input structures were taken from the set of noncovalent complexes crystallised early during the COVID-19 pandemic. In particular, the input PDB: 5R83 was used as the receptor structure for active learning design, and Chimera was used to add hydrogen atoms. The ligand was truncated to include only the pyridyl moiety, as this appeared in other available crystallised fragments in a consistent binding mode (PDB: 5RE4, 5REH, 5R84,