Assessment of methodological quality
Downgraded
As shown in Table There was hetreogenecity in included studies in the type mouthwash (intervention), diagnostic kit, specimen (saliva, nasopharynx, or oropharynx swab) and time of experiment (the time between the first RT-PCR test and using the mouthwash). GRADE system ranked the certainty of the scientific evidence and the strength of the recommendation as moderate for both outcomes (Downgraded for observed heterogeneity) [