He also ate a hamburger and wrote his name on an empty piece of paper in a photo-op. How do you know it was remdesivir rather than the photo-op, hamberder, dexa

He also ate a hamburger and wrote his name on an empty piece of paper in a photo-op. How do you know it was remdesivir rather than the photo-op, hamberder, dexamethasone or regeneron, all of which he got as well?