COS Awards for Excellence Winner: The Virucidal Efficacy of Povidone-Iodine and Chlorhexidine Ophthalmic Solutions Against SARS-CoV-2
FIRST PRIZE - COS Awards of Excellence in Ophthalmic Research - Paper
Authors:Tina Felfeli1, Samantha B. Kasloff2, Jay Krishnan2, Sherif R. El-Defrawy3, Rajeev H. Muni3, Tony Mazzulli4, Todd A. Cutts2. 1Department of Ophthalmology and Vision Sciences and Dalla Lana School of Public Health, University of Toronto, 2Canadian Science Centre for Human and Animal Health and J.C. Wilt Infectious Diseases Research Centre, Public Health Agency of Canada, 3Department of Ophthalmology and Vision Sciences, University of Toronto, 4Department of Laboratory Medicine and Pathobiology, University of Toronto.
Author Disclosure Block:T. Felfeli: None. S.B. Kasloff: None. J. Krishnan: None. S.R. El-Defrawy: None. R.H. Muni: None. T. Mazzulli: None. T.A. Cutts: None.
Shedding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in
ocular secretions of patients with COVID-19 has been reported, which could
serve as a source of infection for ophthalmic staff members. The aim of this
study was to determine the virucidal efficacy and contact times for commonly
used ophthalmic concentrations of povidone-iodine (PVI) and chlorhexidine
gluconate (CHX) against SARS-CoV-2 to help inform the use of pre-procedure
topical antiseptic application for ophthalmologists.
Study Design: Basic medical research.
Methods: Vero E6 cells (American Type Culture Collection) were maintained in cell culture medium and used as indicator cell lines for viable virus. All experiments were conducted using low passage SARS-CoV-2 virus stocks. PVI (5% w/v) and CHX (0.05% w/v) were tested at full strength, 1:4 and 1:16 dilutions in phosphate buffered saline for the efficacy testing. Fifty microliters of the antiseptics were added to 10 ul of SARS-CoV-2 and incubated at room temperature for 1, 5, 10, and 30-minute contact times. A total of three experiments were conducted for PVI and CHX for the four time points with each dilution series consisting of three biological replicates per time point. Viable residual SARS-CoV-2 was determined by the Reed-Muench TCID50 procedure in Vero E6 cells. Cytotoxicity of residual chemical antiseptics was pre-determined in all test concentrations of PVI and CHX on Vero E6 cells to delineate assay limits of detection.
Results: No SARS-CoV-2 was detected with PVI at full strength and 1:4 dilution after 1, 5 and 10-minute contact times. The 1:16 PVI dilution substantially decreased viral titers from 4.45 (SD 0.44) to 0.12 (SD 0.24) log10 TCID50/mL after 1 minute of contact time. No virus was recovered from the inoculated suspensions after 5 and 10 minutes of contact time with 1:16 PVI dilution. Full strength CHX did not result in SARS-CoV-2 inactivation (4.35, SD 0.77 vs 4.1, SD 0.43 log10 TCID50/mL) even after 30 minutes of contact time.
Conclusions: These findings indicate that PVI at commonly used ophthalmic concentrations has more effective virucidal activity than CHX in inactivating SARS-CoV-2 in inoculated suspensions; with CHX proving to be ineffective at full concentration. This has important implications for ophthalmologists when selecting an ophthalmic solution that reduces transmissibility of SARS-CoV-2 amongst patients and healthcare providers.