Evaluation of surface disinfection methods to inactivate the beta coronavirus Murine Hepatitis Virus

Abstract

The list of EPA-approved disinfectants for coronavirus features many products for use on hard, non-porous materials. There are significantly fewer products registered for use on porous materials. Further, many common, high-touch surfaces fall in between non-porous materials such as glass and porous materials such as soft fabrics. The objective of this study was to assess the efficacy of selected commercially available disinfectant products against coronaviruses on common, high-touch surfaces. Four disinfectants (Clorox Total 360, Bleach solution, Vital Oxide, and Peroxide Multi-Surface Cleaner) were evaluated against Murine Hepatitis Virus A59 (MHV) as a surrogate coronavirus for SARS-CoV-2. MHV in cell culture medium was inoculated onto four materials: stainless steel, latex-painted drywall tape, Styrene Butadiene rubber (rubber), and bus seat fabric. Immediately (T0) or 2-hr (T2) post-inoculation, disinfectants were applied by trigger-pull or electrostatic sprayer and either held for recommended contact times (Spray only) or immediately wiped (Spray and Wipe). Recovered infectious MHV was quantified by median tissue culture infectious dose assay. Bleach solution, Clorox Total 360, and Vital Oxide were all effective (>3-log₁₀ reduction or complete kill of infectious virus) with both the Spray Only and Spray and Wipe methods on stainless steel, rubber, and painted drywall tape when used at recommended contact times at both T0 and T2 hr. Multi-Surface Cleaner unexpectedly showed limited efficacy against MHV on stainless steel within the recommended contact time; however, it showed increased (2.3 times greater efficacy) when used in the Spray and Wipe method compared to Spray Only. The only products to achieve a 3-log₁₀ reduction on fabric were Vital Oxide and Clorox Total 360; however, the efficacy of Vital Oxide against MHV on fabric was reduced to below 3-log₁₀ when applied by an electrostatic sprayer compared to a trigger-pull sprayer. This study highlights the importance of considering the material, product, and application method when developing a disinfection strategy for coronaviruses on high-touch surfaces.

Keywords: efficacy; Coronavirus; disinfection.

Figure 1.. Efficacy of bleach solution against MHV.

(A, B) Efficacy (Log₁₀ reduction; left y-axis) of hypochlorite (black bars) or hard water (gray bars) and dynamic range (Log₁₀; patterned bars; right y-axis) when tested against MHV at 0 (A) or 2 hr post-inoculation (B) using a Spray Only application method with a 10-min contact time (see Methods). (C, D) Efficacy of bleach solution or hard water against MHV at 0 (C) or 2 hr (D) post-inoculation when using a Spray and Wipe disinfection method (see Methods). Displayed is the mean and standard deviation. The target 3-log₁₀ reduction is indicated by a dashed line on the y-axis. Statistical significance was determined by 2-way ANOVA. NS, not significant, p > 0.05. *, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001; ****, P ≤ 0.0001. Abbreviations: SS – stainless steel; SBR – rubber; SF – seat fabric; Paint – latex painted drywall tape.

Figure 2.. Efficacy of Clorox Total 360 against MHV.

(A, B) Efficacy (Log₁₀ reduction; left y-axis) of Clorox Total 360 (black bars) or hard water (gray bars) and dynamic range (Log₁₀; patterned bars; right y-axis) when tested against MHV at 0 (A) or 2 hours post-inoculation (B) using a Spray Only application method with a 2-min contact time (see Methods). (C, D) Efficacy of Clorox Total 360 or hard water against MHV at 0 (C) or 2 hr (D) post-inoculation when using a Spray and Wipe disinfection method (see Methods). Displayed is the mean and standard deviation. The target 3-log₁₀ reduction is indicated by a dashed line on the y-axis. Statistical significance was determined by 2-way ANOVA. NS, not significant, p > 0.05. *, P ≤ 0.05; **, P ≤ 0.01; ****, P ≤ 0.0001. Abbreviations: SS – stainless steel; SBR – rubber; SF – seat fabric; Paint – latex painted drywall tape.

Figure 3.. Efficacy of oxide-based disinfectants against MHV.

(A, B) Efficacy (Log₁₀ reduction; left y-axis) of Peroxide Multi-Surface Cleaner (black bars) or hard water (gray bars) and dynamic range (Log₁₀; striped bars; right y-axis) when tested against MHV at T0 hr using either a Spray Only method with a 30-sec contact time (A) or a Spray and Wipe disinfection method (B; see Methods). (C, D) Efficacy of Vital Oxide (dotted bars) or hard water (gray bars) when tested against MHV at T0 hr using either a Spray Only method with a 5-min contact time (C) or a Spray and Wipe disinfection method (D; see Methods). Displayed is the mean and standard deviation. The target 3-log₁₀ reduction is indicated by a dashed line on the y-axis. Statistical significance was determined by 2-way ANOVA. *, P ≤ 0.05; **, P ≤ 0.01; ****, P ≤ 0.0001. Abbreviations: SS – stainless steel; SBR – rubber; SF – seat fabric; Paint – latex painted drywall tape.

Figure 4.. Effect of spray application method on disinfectant efficacy.

(A, B) Efficacy (Log₁₀ reduction; left y-axis) of Peroxide Multi-Surface Cleaner (black bars) or hard water (gray bars) and dynamic range (Log₁₀; striped bars; right y-axis) when tested against MHV at T0 hr on stainless steel (A) or a seat fabric (B) applied by trigger-pull or ESS and held for a contact time of 30 sec (Spray Only method). (C, D) Efficacy of Vital Oxide (dotted bars) or hard water (gray bars) when tested against MHV at T0 hr on stainless steel (C) or seat fabric (D) applied by trigger-pull or ESS and held for a contact time of 5 min (Spray Only method). Displayed is the mean and standard deviation. The target 3-log₁₀ reduction is indicated by a dashed line on the y-axis. Statistical significance was determined by 2-way ANOVA. NS, not significant, p > 0.05. **, P ≤ 0.01; ****, P ≤ 0.0001.