Disinfectant Efficacy Against SARS-CoV-2 Surrogates, Bovine Coronavirus and Human Coronavirus OC43, on Hard and Soft Non-porous Surfaces

The novel human coronavirus (HCoV), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), emerged from Wuhan, China in the latter part of 2019. The rapid spread of SARS-CoV-2 amid the most recent COVID-19 pandemic forced countless foodservice establishments (FSEs) across the United States to close, taking a tremendous toll on the foodservice industry. Although primarily transmitted person-to-person, previous studies indicate that the duration of SARS-CoV-2 survival on different environmental surfaces provides adequate time for secondary transmission to occur. To prevent the further spread of SARS-CoV-2, effective disinfection of surfaces in FSEs is necessary. While disinfectants approved for use against SARS-CoV-2 are found on the Environmental Protection Agency’s (EPA’s) List N, there is limited data available regarding the efficacy of these products against two SARS-CoV-2 surrogates, bovine coronavirus (BCoV) and human coronavirus OC43 (HCoV OC43) on surfaces other than glass and stainless steel. Therefore, our aims for this study were to (I) optimize a neutralization method for chlorine- and quaternary ammonium compound (QAC)-based disinfectants during efficacy testing, (II) determine the efficacy of two separate batches of three ready-to-use (RTU) spray disinfectants of different active ingredients (chlorine, hydrogen peroxide, and QAC + alcohol) against SARS-CoV-2 surrogates, BCoV and HCoV OC43, in suspension and (III) on surfaces commonly found in the ‘front-of-the-house’ in FSEs (polyethylene terephthalate [PET] plastic and vinyl upholstery fabric). Cytotoxicity to the host cell line during efficacy testing was successfully eliminated via infection media paired with centrifugation in PierceTM detergent removal columns for the QAC-based disinfectant, and a 5% fetal bovine serum (FBS) + 1% sodium thiosulfate (Na2S2O3) solution for the chorine-based disinfectant. In suspension testing, all three RTU disinfectants tested achieved a \u3e3.0 log10 reduction of BCoV and HCoV OC43 within 2 min. On PET carriers, all three RTU disinfectants reduced BCoV by \u3e3.0 log10 TCID50/mL, whereas Oxivir Tb was the only disinfectant efficacious against BCoV on vinyl carriers. None of the three RTU disinfectants tested achieved a \u3e3.0 log10 reduction of HCoV OC43 on PET or vinyl. However, after a 2 min contact time, all three disinfectants reduced the infectivity of BCoV and HCoV OC43 below the limit of detection (LOD) on both PET and vinyl surfaces. Those cases with \u3c3.0 log10 reduction of virus titer were due to the decreased dynamic range on the carrier prior to disinfection. Further analysis of carrier test results revealed that the mean reduction in titer of BCoV and HCoV OC43 after drying was greater on vinyl carriers. In addition, greater amounts of reduction of BCoV and HCoV OC43 were observed on both PET and vinyl carriers as the relative humidity (RH) level increased. At low RH (20-29%) conditions, the reduction in the titer of HCoV OC43 was significantly greater than that of BCoV on both PET and vinyl carriers. Our data showed that both SARS-CoV-2 surrogates are very sensitive to the tested disinfectants, and further analysis of the quantitative carrier test data indicates that additional factors (i.e., surface type, RH, and surrogate) must be carefully considered when performing disinfectant efficacy testing on carriers. Collectively, these data highlight the importance of verifying disinfectant suspension test data by performing disinfectant carrier tests which expose the virus and disinfectant to conditions (i.e., surface type, relative humidity, surrogate) similar to those encountered during ‘real-world’ application