# Effectiveness of mouthwashes to reduce the SARS-COV-2 load in saliva of adults with diagnosis of COVID-19: Systematic review and meta-analysis

## TL;DR

This study reviews whether mouthwashes can reduce SARS-CoV-2 viral load in saliva of adults with COVID-19.

## Contribution

It provides a meta-analysis comparing the effectiveness of three mouthwash types in reducing viral load.

## Key findings

- Overall, mouthwashes did not significantly reduce SARS-CoV-2 viral load in saliva.
- Povidone-iodine (PVP-I) showed a significant reduction in viral load compared to other mouthwashes.
- Cetylpyridinium chloride (CPC) and chlorhexidine (CHX) did not show significant reductions in viral load.

## Abstract

COVID-19 still represents a threat to public health. In this sense, antiseptic mouthwashes have been suggested to reduce cross-contamination and community transmission.

This systematic review and meta-analysis aimed to synthesize the evidence on the effectiveness of povidone-iodine (PVP-I), cetylpyridinium chloride (CPC) and chlorhexidine (CHX) mouthwashes in reducing SARS-COV-2 viral load in the saliva of adults diagnosed with COVID-19. After the systematic search in five electronic databases, 16 clinical trials published until June 2023 were analyzed. Of these, 6 were included in the meta-analysis.

The standardized mean difference (SMD) was reported with its corresponding 95% confidence intervals (95%CI). An overall SMD of 0.51 (95%CI: -0.29 to 1.32; I² = 46.0%; p = 0.047) was found. For CPC, the combined effect found in the studies was not significant (SMD = -0.07; 95%CI: -0.42 to 0.28; I² = 0.0%; p = 0.373); the same occurred for CHX (SMD = 0.50; 95%CI: -43.32 to 44.32; I² = 0.0%; p = 1.000). However, PVP-I showed a more consistent profile with a significant combined effect (SMD = 4.15; 95%CI: 2.11 to 6.18) and negligible heterogeneity (I² = 0.0%; p = 0.908).

The findings indicate a non-significant effect of mouthwashes on reducing viral load when all types were evaluated together. Separately, only PVP-I showed a significant reduction in viral load with a low level of certainty of evidence, while for CPC and CHX the reduction was not significant, with a low and very low level of certainty of evidence, respectively.

Key words:SARS-CoV-2, mouthwashes, povidone-iodine, cetylpyridinium, chlorhexidine.