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

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 .