Evaluating the virucidal activity of four disinfectants against SARS-CoV-2

Abstract

Background: The recent COVID-19 pandemic highlights the need for efficacious virucidal products to limit the spread of SARS-CoV-2. Several studies have suggested that alcohol-based sanitizers and some disinfectants are effective. While virucidal activity data of low-level disinfectants are lacking and some conclusions are not clear yet.

Methods: We evaluated the virucidal activity of 2 quaternary ammonium compounds (QAC) disinfectants (MICRO-CHEM PLUS and FWD), W30 (an amphoteric surfactant), and Medical EtOH against SARS-CoV-2. Suspension tests covering different concentration and contact time were performed using the integrated cell culture-qPCR method.

Results: Each of disinfectants was effective at inactivating SARS-CoV-2. MCP and FWD are highly effective within 15 seconds. W30 is also efficient within 2 minutes at concentration of 1%. Consistent with previous report, our results also demonstrated that 38% ethanol was sufficient to completely inactivate virus, which proved the method used in this study is feasible.

Conclusions and discussion: QAC disinfectants, MCP and FWD, are highly effective for the inactivation of SARS-CoV-2, which making them practical for use in health care setting and laboratories where prompt disinfection is important. The low-level disinfectant based on amphoteric surfactant, W30, which may present in commonly available household hygiene agents is also able to inactivate SARS-CoV-2.

Keywords: COVID-19; Integrated cell culture-qPCR method; Quaternary ammonium compounds disinfectant; SARS-CoV-2; Virucidal activity.

Fig 1

Q-PCR standard curve for SRAS-CoV-2. The virus stock was serial diluted (1:10) and viral RNAs were extracted from these serial dilutions. Ct values of the range of dilutions covering 8 gradients were used to draw the standard curve. The corresponding virus titre was calculated based on the standard curve.

Fig 2

Virucidal activity of MCP, FWD, W30, and medical ethanol against SARS-CoV-2. The biocide concentrations ranged from about 0.06% to 5% (MCP, FWD, W30) or 20% to 100% (medicinal alcohol, 95%) with an exposure time form 15 seconds to 8 minutes. CPE of infected cells in each test was observed after 3 days postinfection. Efficacy of four disinfectants against SARS-CoV-2 was addressed by quantitative suspension assay and residual infectivity was determined by virus titer using quantitative RT-PCR (qPCR). (A) MCP. (B) (FWD. (C) W30. (D) Medical ethanol.

Fig. 3

Virucidal activity of MCP and medical ethanol against SARS-CoV-2. The biocide concentrations ranged from about 0.06% to 5% or 20% to 100% of medicinal alcohol (95%) with an exposure time form 15 seconds to 8 minutes. CPE of infected cells in each test was observed after virus incubation for different time with different final concentration of four disinfectants. The residual infectivity was determined by virus titer using plaque assay. (A) MCP. (B) Medical ethanol.