AND LEAVES YOU FEELING MINTY FRESH: Mouthwash Kills Coronavirus In 30 Seconds, According To Study. “The Cardiff University study, which has yet to be peer reviewed, found that mouthwashes with at least .07 percent cetylpyridinium chloride (CPC) showed ‘promising signs’ of combatting the virus, according to Science Focus. CPC-based mouthwashes eradicated the virus when exposed in a laboratory, but the trial has yet to be conducted with saliva.”