In Vitro Evaluation of the Virucidal Activity of Different Povidone–Iodine Formulations Against Murine and Human Coronaviruses

INTRODUCTION: Polyvinylpyrrolidone–iodine (PVP-I) demonstrates broad-spectrum anti-infective activity and is available in different formulations for oral rinse and topical use in medical and personal care settings. The novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has underscored the need to supplement available preventive strategies. METHODS: We assessed virucidal activity of PVP-I formulations, including 0.5% (w/v) solution, 5.0% (w/v) solution, 7.5% (w/v) scrub, and 10.0% (w/v) solution, versus placebos when challenged with coronaviruses in two in vitro studies. Murine coronavirus strain A59 (American Type Culture Collection [ATCC](®) VR-764™), human coronavirus strain OC43 (ZeptoMetrix Corp. #0810024CF), human coronavirus strain NL63 (ZeptoMetrix Corp. #0810228CF), and human coronavirus strain 229E (ATCC(®) VR-740™) were used as surrogates for SARS-CoV-2. Both studies used the American Society for Testing and Materials in vitro time-kill method. RESULTS: All active PVP-I formulations in study 1 demonstrated virucidal activity at 15 s, with mean log(10) reduction of greater than 4.56 or greater than 99.99% inactivation; a cytotoxic effect against the National Collection of Type Cultures clone 1469 host cells was observed with 5.0% (w/v) solution, 7.5% (w/v) scrub, and 10.0% (w/v) solution. Active PVP-I formulations in study 2 demonstrated effective virucidal activity against coronaviruses in less than 15 s; log(10) reduction in viral titer for each coronavirus strain was consistently higher for 10.0% (w/v) solution and 0.5% (w/v) solution versus 7.5% (w/v) scrub. CONCLUSION: Both studies demonstrated in vitro virucidal activity of PVP-I formulations when challenged with SARS-CoV-2 surrogate coronaviruses. Although promising, further investigations are needed to evaluate SARS-CoV-2 inactivation.