Disinfection effect of ozonated water on SARS-CoV-2 in the presence of salivary proteins

Ozonated water is expected to be an effective disinfectant for SARS-CoV-2 present on environmental fomites; however, ozone is consumed by organic substances, resulting in attenuation of its effect. SARS-CoV-2 present in saliva can contaminate environmental surfaces; therefore, it is essential to understand the effect of organic substances in saliva on the disinfectant properties of ozonated water. To assess organic factors in saliva and the extent to which they diminish the effect of ozonated water on SARS-CoV-2. Ozonated water was exposed to salivary organic factors and residual ozone concentrations were measured. SARS-CoV-2 was exposed to a salivary factor and virus inactivation by ozonated water was measured. Amylase and mucin consumed ozone in a concentration-dependent manner. Urea did not. Ozonated water appeared to inactivate SARS-CoV-2 within 30 s. The amount of inactivated SARS-CoV-2 decreased as the protein concentration increased. Virus inactivation was stronger by 1.5 mg/L ozonated water than by 0.5 mg/L ozonated water. This study suggests that the salivary amylase and mucin decay ozone in a concentration-dependent manner, thereby attenuating the disinfection properties of ozonated water for SARS-CoV-2. An increase of the initial amount of ozone can ameliorate the disinfection effect of ozonated water on SARS-CoV-2. Ozone consumption should be taken into consideration for virus infection control. These results provide fundamental information about the effect of ozonated water when used to decontaminate surfaces harbouring SARS-CoV-2 in saliva.