Comparative Evaluation of the Inactivation of SARS-CoV-2 and Human Coronavirus 229E against Sodium Hypochlorite

Surface disinfection is one of the important non-pharmaceutical intervention measures that help prevent the spread of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Disinfectants with an efficacy claim against Human Coronavirus strain 229E (HCoV-229E) have been used for the disinfection of SARS-CoV-2; however, the comparative susceptibility of these two viruses to chemical disinfection has not been well defined. To address this, laboratory data were generated to compare the level of inactivation of human coronaviruses HCoV-229E and SARS-CoV-2 to a common antimicrobial agent, sodium hypochlorite (NaOCl), on a hard non-porous surface. A hard surface-based Quantitative Method (QM) was used to evaluate the viral inactivation efficacy by three treatments of NaOCl against HCoV-229E and SARS-CoV-2. For each treatment, viral inoculum containing soil load was applied onto a stainless steel carrier and dried. The inoculated carrier was exposed to NaOCl or a control fluid and held for five minutes. Following the exposure time, a neutralizer was added, and the sample was serially diluted and inoculated onto host cells to determine the number of infective units. The resulting Log10 of the density for control and treated carriers was used to generate Log10 reduction (LR) values for comparative statistical evaluation. The mean LR ± standard error (SE) for HCoV-229E was 0.96 ± 0.09 (n=10) at 500 ppm NaOCl, 2.41 ± 0.15 (n=10) at 1,000 ppm NaOCl, and 4.54 ± 0.13 (n=10) at 1,500 ppm NaOCl. The mean LR ± SE for SARS-CoV-2 was 0.91 ± 0.24 (n=4) at 500 ppm NaOCl, 1.96 ± 0.26 (n=4) at 1,000 ppm NaOCl, and 4.23 ± 0.16 (n=4) at 1,500 ppm NaOCl. Both viruses were significantly responsive to the increasing concentrations of NaOCl. HCoV-229E had slightly higher mean LRs compared to SARS-CoV-2 at each NaOCl concentration; however, these differences were not statistically significant (p ≥ 0.067). Regression analysis using a linear mixed effects model (LMM) also indicates that the susceptibility of HCoV-229E and SARS-CoV-2 to NaOCl is comparable. Understanding the antimicrobial tolerance of viruses can enhance public health response to viral infections. By determining the tolerance, the most appropriate antimicrobial agent can be chosen to disinfect surfaces contaminated with viral particles. Disinfection of highcontact surfaces can reduce the amount of fomite transmission and limit outbreaks. The data suggest that HCoV-229E and SARS-CoV-2 are statistically comparable in their susceptibility to NaOCl treatments.