Efficacy of detergent-based cleaning and wiping against SARS-CoV-2 on high-touch surfaces

Abstract

Efficacy of cleaning methods against SARS-CoV-2 suspended in either 5% soil load (SARS-soil) or simulated saliva (SARS-SS) was evaluated immediately (hydrated virus, T0) or 2 hours post-contamination (dried virus, T2). Hard water dampened wiping (DW) of surfaces, resulted in 1.77-3.91 log reduction (T0) or 0.93-2.41 log reduction (T2). Incorporating surface pre-wetting by spraying with a detergent solution (D + DW) or hard water (W + DW) just prior to dampened wiping did not unilaterally increase efficacy against infectious SARS-CoV-2, however, the effect was nuanced with respect to surface, viral matrix, and time. Cleaning efficacy on porous surfaces (seat fabric, SF) was low. W + DW on stainless steel (SS) was as effective as D + DW for all conditions except SARS-soil at T2 on SS. DW was the only method that consistently resulted in > 3-log reduction of hydrated (T0) SARS-CoV-2 on SS and ABS plastic. These results suggest that wiping with a hard water dampened wipe can reduce infectious virus on hard non-porous surfaces. Pre-wetting surfaces with surfactants did not significantly increase efficacy for the conditions tested. Surface material, presence or absence of pre-wetting, and time post-contamination affect efficacy of cleaning methods.

Keywords: SARS-CoV-2; cleaning; coronavirus; disinfection; high-touch surfaces; surfactant; virucide; virus.

Figure 1.

Recovery of SARS-CoV-2 suspended in 5% Soil Load. Recovery of SARS-CoV-2 suspended in a 5% soil load from coupon materials after treatment (a) immediately (T0) and (b) 2 hours (T2) post-inoculation. Data are grouped by material along the x-axis. Bars are arranged by treatment, with surface wetting with detergents followed by hard water dampened wiping (D + DW), Dawn (black bars), and Tide (light grey bars); surface wetting with hard water followed by hard water dampened wiping (W + DW) (dark grey bars), and hard water dampened wiping only (DW, white bars) methods indicated for each material. The dynamic range for each material is represented in the dot patterned bars. The dotted horizontal line demarcates the 3-log reduction efficacy performance target for disinfectants. Significant differences within each material were determined via the Holm-Sidak method. P-values are represented on graphs as: P ≤ 0.05 *, P ≤ 0.01 **, P ≤ 0.001 ***.

Figure 2.

Recovery of SARS-CoV-2 suspended in Simulated Saliva. Recovery of SARS-CoV-2 suspended in simulated saliva from coupon materials after treatment (a) immediately (T0) and (b) 2 hours (T2) post-inoculation. Data are grouped by material along the x-axis. Bars are arranged by treatment, with surface wetting with detergents followed by hard water dampened wiping (D + DW), Dawn (black bars), and Tide (light grey bars); surface wetting with hard water followed by hard water dampened wiping (W + DW) (dark grey bars), and hard water dampened wiping only (DW, white bars) methods indicated for each material. The dynamic range for each material is represented in the dot patterned bars. The dotted horizontal line demarcates the 3-log reduction efficacy performance target for disinfectants. Significant differences within each material were determined via the Holm-Sidak method. P-values are represented on graphs as: P ≤ 0.05 *, P ≤ 0.01 **, P ≤ 0.001 ***.