There is no evidence in the literature to support that sildenafil has direct antiviral activity but studies hypothesize that through host pathways it could relieve symptoms . However there is a clinical trial ( NCT04304313 ) that investigates the efficacy of sildenafil against placebo, In addition to that vardenafil also binds the same pocket predicted both in PocketMatch and SwissDock general docking. Even though vardenafil have better docking results (-9.27) than sildenafil (-8.55) this docking protocol can't be trusted to handle the process of choosing one over the other. I highly recommend further accurate docking and molecular dynamic to choose between sildenafil and vardenafil for clinical trials.