The Role of Chlorhexidine in Minimizing the Viral Load Among COVID-19 Patients: A Randomized Controlled Clinical Trial
Phase: PHASE4
Conditions: COVID-19
Sponsor: King Abdulaziz University

1 
 
Short-term Efficacy of Chlorhexidine and 
Povidone-Iodine Mouth Rinses in 
Reducing Salivary SARS-CoV-2 Viral Load: 
A Randomized Controlled Clinical Trial 
NCT04941131 
June 24, 2021 
 
 
Dr. Zuhair Natto 
 
 

2 
 
1. Background and Rationale 
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is primarily transmitted 
through respiratory droplets and aerosols. Dental procedures pose a significant transmission risk 
due to close proximity to the oral cavity and aerosol generation. Saliva has been identified as a 
potential reservoir for SARS-CoV-2. Therefore, reducing viral load in saliva prior to dental 
treatment may reduce the risk of cross-infection. 
Several antiseptic mouth rinses have been proposed as preprocedural interventions to reduce 
viral load in the oral cavity. This study evaluates and compares the short-term effects of 
chlorhexidine (in both rinse and lozenge forms) and povidone-iodine mouth rinse on salivary 
viral load in confirmed COVID-19 patients. 
 
 
2. Objectives 
Primary Objective 
• 
To evaluate the short-term efficacy of different mouth rinses and lozenges (chlorhexidine 
rinse, chlorhexidine lozenges, and povidone iodine rinse) in reducing salivary SARS-
CoV-2 viral load. 
Secondary Objective 
• 
To compare each intervention with saline as a control. 
• 
To assess changes in viral load using Ct values of E and S genes via RT-PCR. 
 
Material and methods: 
3. Study Design 
• 
This study is a four-arm, open-label, randomized controlled clinical trial designed to 
evaluate the short-term efficacy of three oral antiseptic interventions—chlorhexidine 
digluconate mouth rinse, chlorhexidine digluconate lozenges, and povidone-iodine (PVP-

3 
 
I) mouth rinse—compared to a saline control in reducing salivary SARS-CoV-2 viral 
load in COVID-19-positive patients. 
• 
Type of Study: Open-label, randomized controlled clinical trial 
• 
Study Setting: King Fahad General Hospital and Al-Hamra Community Health Center, 
Jeddah, Saudi Arabia 
• 
Registration: ClinicalTrials.gov (NCT04941131) 
• 
Ethical Approval: Jeddah Health Affairs (#1485) 
 
Study Design 
Randomization and Blinding 
• 
Randomization: Participants will be allocated using a simple 1:1:1:1 randomization 
schedule generated via computer-based random number sequencing. 
• 
Allocation Concealment: Allocation will be performed using sealed opaque envelopes. 
• 
Blinding: This is an open-label study due to the obvious physical and functional 
differences between interventions (rinse vs. lozenge), which preclude participant and 
clinician blinding. However, the laboratory personnel and statisticians will be blinded 
to group allocation. 
 
4. Participants 
Inclusion Criteria: 
• 
Adults aged ≥18 years 
• 
Positive nasopharyngeal RT-PCR for SARS-CoV-2 
• 
Ability to provide informed consent 
Exclusion Criteria: 
• 
Known allergy to study substances (chlorhexidine or povidone-iodine) 
• 
Pregnancy 

4 
 
• 
Prior COVID-19 treatment 
• 
Severe oral lesions that contraindicate rinse use 
 
 
5. Interventions 
Participants were randomized into four arms: 
1. Chlorhexidine Mouth Rinse (CHX): 
10 mL undiluted solution, used for 30 seconds. 
2. Chlorhexidine Lozenges (CHX Lozenges): 
2 mg lozenge to dissolve slowly in the mouth. 
3. Povidone Iodine Mouth Rinse (PVP-I): 
10 mL undiluted solution, used for 30 seconds. 
4. Control (Saline): 
10 mL normal saline rinse, used for 30 seconds. 
All participants were instructed to refrain from eating, drinking, or oral hygiene procedures for at 
least 30 minutes before the intervention. 
 
 
6. Sample Collection and Laboratory Testing 
• 
Saliva Collection: Passive drool technique; 3 mL of saliva collected before and after 
intervention (5 minutes apart). 
• 
Analysis Method: 
Real-time RT-PCR using LabGun COVID-19 Kit (Biosewoom, Korea). 
o Targets: E gene and S gene 
o Measurement: Threshold cycle (Ct) values 
 

5 
 
7. Sample Size Calculation 
• 
Software: G*Power 3.1 
• 
Effect size: 1.1 
• 
Power: 80% 
• 
Alpha: 0.05 
• 
Required Sample: 15 participants per group (Total N = 60) 
Sample Size Justification: 
• 
Based on an expected moderate-to-large effect size (Cohen’s f = 0.4), α = 0.05, power = 
0.80, and four groups: 
o Required sample = 60 participants (15 per group) 
o Power calculation was performed using G*Power 3.1. 
• 
To account for 10% attrition, a total of 66 participants will be recruited. 
 
 
8. Statistical Analysis 
Statistical Analysis 
Software: 
• 
Data will be analyzed using IBM SPSS Statistics version 25 and R (v4.3 or later) for 
confirmatory and exploratory analyses. 
Analysis Population: 
• 
Intention-to-treat (ITT): All randomized participants will be included in the primary 
analysis, with imputation for missing data. 
 
Primary Outcome Analysis: 
• 
Primary Endpoint: 
o Change in Ct value of SARS-CoV-2 E and S genes from baseline to post-
intervention (ΔCt). 

6 
 
• 
Between-Group Comparison: 
o One-way ANOVA to assess differences in mean ΔCt across all four groups. 
o Post-hoc Bonferroni test for pairwise comparisons. 
o If assumptions of ANOVA are violated, Kruskal–Wallis test with Dunn’s test 
for post-hoc comparisons will be used. 
• 
Within-Group Comparison: 
o Paired t-test to compare pre- and post-intervention Ct values within each group. 
o Wilcoxon signed-rank test will be used if normality is not met. 
 
Assumptions and Validation: 
• 
Normality: Assessed using Shapiro-Wilk test and QQ plots. 
• 
Homogeneity of variance: Evaluated using Levene’s test. 
• 
Effect Size Reporting: Partial η² for ANOVA, Cohen’s d for t-tests. 
 
Missing Data Handling: 
• 
For the ITT analysis, missing outcome data will be handled using multiple imputation 
(MI) under the assumption of missing at random (MAR). 
• 
Sensitivity analyses using last observation carried forward (LOCF) will be conducted 
to assess the robustness of findings. 
 
9. Expected Outcomes 
• 
Povidone-iodine rinse will demonstrate the highest reduction in viral load. 
• 
Chlorhexidine lozenges may show moderate efficacy. 
• 
Chlorhexidine rinse may show variable outcomes. 
• 
Control (saline) is expected to have no significant effect. 
 

7 
 
10. Ethical Considerations 
• 
All participants provided informed written consent. 
• 
Ethical approval was secured from local ethics board. 
• 
All data were anonymized and securely stored. 
• 
Participants had the right to withdraw at any time without consequences. 
 
11. Timeline 
Phase 
Duration 
Ethical Approval 
Completed 
Participant Recruitment 
2 months 
Data Collection 
2 months 
Laboratory Analysis 
Concurrent 
Data Analysis & Manuscript 1 month 
 
12. Dissemination Plan 
The study results will be disseminated through: 
• 
Peer-reviewed publication 
• 
Scientific conferences 
• 
Institutional and ministry health updates 

8 
 
References 
1. Afeef, M., Al-Harbi, S., Nassar, M. S., Alhetheel, A. F., & Ashi, H. (2022). The short-term effect of 
different chlorhexidine forms versus povidone iodine mouth rinse in minimizing the oral SARS-
CoV-2 viral load: An open label randomized controlled clinical trial study. Medicine, 101(30), 
e28925.   
2. Elzein, R., Abdel-Sater, F., Fakhreddine, S., Hanna, E., Feghali, R., Hamad, H., & Ayoub, F. (2021). 
In vivo evaluation of the virucidal efficacy of chlorhexidine and povidone-iodine mouthwashes 
against salivary SARS-CoV-2: A randomized-controlled clinical trial. Journal of Evidence-Based 
Dental Practice, 21(3), 101584.  
3. Sánchez Barrueco, Á., Mateos-Moreno, M. V., Martínez-Beneyto, Y., García-Vázquez, E., Campos 
González, A., Zapardiel Ferrero, J., & Alcalá Rueda, I. (2022). Effect of oral antiseptics in reducing 
SARS-CoV-2 infectivity: Evidence from a randomized double-blind clinical trial. Emerging 
Microbes & Infections, 11(1), 1833–1842.  
4. Perussolo, J., Teh, M.-T., Gkranias, N., Tiberi, S., Petrie, A., Cutino-Moguel, M.-T., & Donos, N. 
(2023). Efficacy of three antimicrobial mouthwashes in reducing SARS-CoV-2 viral load in the 
saliva of hospitalized patients: A randomized controlled pilot study. Scientific Reports, 13, 
12647.   
5. Seneviratne, C. J., Balan, P., Ko, K. K. K., Udawatte, N. S., Goh, B. T., & Ng, L. C. (2021). Efficacy of 
commercial mouth-rinses on SARS-CoV-2 viral load in saliva: Randomized control trial in 
Singapore. Infection, 49(2), 305–311.   
6. Gül, S. N. S., Dilsiz, A., Sağlık, İ., & Aydın, N. N. (2022). Effect of oral antiseptics on the viral load 
of SARS-CoV-2: A randomized controlled trial. Dental and Medical Problems, 59(3), 357–363.   
7. Ferrer, M. D., Barrueco, Á. S., Martínez-Beneyto, Y., Mateos-Moreno, M. V., Ausina-Márquez, V., 
García-Vázquez, E., & Puche-Torres, M. (2021). Clinical evaluation of antiseptic mouth rinses to 
reduce salivary load of SARS-CoV-2. Scientific Reports, 11(1), 24392.   
8. Costa, D. D., Brites, C., Vaz, S. N., de Santana, D. S., dos Santos, J. N., & Cury, P. R. (2021). 
Chlorhexidine mouthwash reduces the salivary viral load of SARS-CoV-2: A randomized clinical 
trial. Oral Diseases, 28(Suppl 2), 2500–2508.