Mouthrinses and SARS-CoV-2 viral load in saliva: a living systematic review

Objective To conduct a living systematic review of the clinical evidence about the effect of different mouthrinses on the viral load of SARS-CoV-2 in the saliva of infected patients. Methods This study was reported using the PRISMA guidelines. An electronic search was conducted in seven databases and preprint repositories. We included human clinical trials that evaluated the effect of mouthrinses with antiseptic substances on the viral load of SARS-CoV-2 in the saliva of children or adults, who tested positive for SARS-CoV-2 by reverse transcriptase-polymerase chain reaction (RT-PCR). The risk of bias was assessed using the ROBINS-I tool. PROSPERO registration number: CRD42021240561. Results Five studies were included (n = 66 participants). Study participants underwent oral rinses with hydrogen peroxide (H2O2) at 1%, povidone-iodine (PI) at 0.5% or 1%, chlorhexidine gluconate (CHX) at 0.2% or 0.12%, cetylpyridinium chloride (CPC) at 0.075%, and Linolasept. Only one study included a control group with sterile water. Three of the studies identified a reduction in viral load in saliva after the use of mouthrinses with PI (up to three hours), CHX (up to four hours), or Linolasept mouthwash (up to six hours). One study reported a statistically significant reduction after the use of mouthrinses with CPC or PI vs water (up to six hours) and one study reported a non-significant reduction in viral load after the use of H₂O₂ rinses. Conclusions According to the present systematic review, the effect of mouthrinses on SARS-CoV-2 viral load in the saliva of COVID-19 patients remains uncertain. Evidence from well-designed randomised clinical trials is required for further and more objective evaluation of this effect.