OC43-HR2P, a peptide derived from heptad repeat 2 regions of S2 domain of HCoV-OC43 and its optimized form EK1, showed pan-CoV fusion inhibition property.[39] The structure (protein data bank [PDB] ID 5ZUV and 5ZVM) shows a stable 6-helix bundle structure with α-HCoV and long β-HCoV-HR1 domain.[39]