Comparative evaluation of chlorous acid and sodium hypochlorite activity against SARS-CoV-2

Abstract

A novel coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), suddenly emerged in China in 2019, spread globally and caused the present COVID-19 pandemic. Therefore, to mitigate SARS-CoV-2 infection effective measures are essential. Chlorous acid (HClO2) has been shown to be an effective antimicrobial agent. However, at present there is no experimental evidence showing that HClO2 can inactivate SARS-CoV-2. Therefore, in this study, we examined the potential of HClO2 to inactivate SARS-CoV-2 in presence or absence of organic matter and the results were compared with that of sodium hypochlorite (NaClO), another potent antimicrobial agent. When concentrated SARS-CoV-2 was incubated with 10 ppm HClO2 for 10 s, viral titre was decreased by 5 log of 50% tissue culture infective dose per mL (TCID50 ml−1). However, the same concentration of NaClO could not inactivate SARS-CoV-2 as effectively as HClO2 did even after incubation for 3 min. Furthermore, 10 ppm HClO2 also inactivated more than 4.0 log of TCID50 within 10 s in the presence of 5 % fetal bovine serum used as mixed organic matters. Our results obtained with HClO2 are more effective against SARS-CoV-2 as compared to NaClO that can be used for disinfectant against SARS-CoV-2 .

Efficacy of Peracetic Acid and Sodium Hypochlorite against SARS-CoV-2 on Contaminated Surfaces

“…Our data indicated that in the absence of a soil load, NaOCl at 50 ppm for 1 min resulted in 5 log reduction. The latter is a much lower concentration than reported by Chin et al and Chan et al ( 16 , 48 ), in line with 10 ppm for 3 min reported by Hatanaka et al ( 49 ), but higher than the 1.5 ppm for 30 s reported by Brown et al ( 50 ).…”

“…These studies reported a wide range of results to achieve >3 log reduction in SARS-CoV-2. For example, in the absence of soil load, 10% bleach (unknown ppm for NaOCl) for 1 min resulted in 3.25 log reduction ( 48 ), 1:99 dilution of bleach (unknown ppm for NaOCl) for 5 min resulted in 4.8 log reduction ( 16 ), 10 ppm for 3 min resulted in 3 to 4 log ( 49 ), and 1.5 ppm for 30 s resulted in ~4 log reduction ( 50 ). Chin et al and Chan et al ( 16 , 48 ) did not consider the buffering effect of infection media in virus stocks on NaOCl.…”

“…Chin et al and Chan et al ( 16 , 48 ) did not consider the buffering effect of infection media in virus stocks on NaOCl. To avoid the buffering effect observed on NaOCl at low concentrations, Brown et al ( 50 ) generated their SARS-CoV-2 stock in a saline solution, while Hatanaka et al ( 49 ) concentrated their virus stocks using polyethylene glycol and resuspended the viruses in PBS. To overcome this issue, the stock generated in our study was ultrafiltered to concentrate the viruses, while semi-purifying them from cell culture lysates ( 51 ).…”

Elucidation of composition of chlorine compounds in acidic sodium chlorite solution using ion chromatography

“…One candidate among chlorinated compounds is chlorous acid solution [ 8 ]. Chlorous acid (HClO 2 ) has a structure with one more oxygen than hypochlorous acid.…”

Virus purification highlights the high susceptibility of SARS-CoV-2 to a chlorine-based disinfectant, chlorous acid

“…In recent years, various chlorine-based disinfectants, such as chlorine dioxide, sodium hypochlorite, and chlorous acid solutions, have been shown to exhibit antiviral effects against SARS-CoV-2 [6][7][8][9]. This is because chlorine ions are potent oxidizing agents that induce denaturation of microbial proteins [10]; however, chlorine ions rapidly lose their antimicrobial activity upon contact with organic matter [11].…”