Hypochlorous acid solution is a potent antiviral agent against SARS-CoV-2.

Aim A novel coronavirus, termed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) suddenly appeared in Wuhan, China, and has caused pandemic. In this study, we evaluated antiviral activity of purified hypochlorous acid (HClO) against coronaviruses such as SARS-CoV-2 and transmissible gastroenteritis virus (TGEV) responsible for pig diseases. Materials and results In a suspension test, 28.1 ppm HClO solution inactivated SARS-CoV-2 in phosphate-buffered saline with the reduction of 104 of 50% tissue culture infectious dose per ml (TCID50 per ml) within 10 s. When its concentration increased to 59.4 ppm, the virus titre decreased to below the detection limit (reduction of 5 logs TCID50 ) within 10 s even in the presence of 0.1% foetal bovine serum. In a carrier test, incubation with 125 ppm HClO solution for 10 min or 250 ppm for 5 min inactivated SARS-CoV-2 by more than 4 logs TCID50 per ml or below the detection limit. Because the titre of TGEV was 10-fold higher, TGEV was used for SARS-CoV-2 in a suspension test. As expected, 56.3 ppm HClO solution inactivated TGEV by 6 logs TCID50 within 30 s. Conclusions In a carrier test, 125 ppm HClO solution for 10 min incubation is adequate to inactivate 4 logs TCID50 per ml of SARS-CoV-2 or more while in a suspension test 56.3 ppm HClO is adequate to inactivate 5 logs TCID50 per ml of SARS-CoV-2 when incubated for only 10 s regardless of presence or absence of organic matter. Significance and impact of the study Effectiveness of HClO solution against SARS-CoV-2 was demonstrated by both suspension and carrier tests. HClO solution inactivated SARS-CoV-2 by 5 logs TCID50 within 10 s. HClO solution has several advantages such as none toxicity, none irritation to skin and none flammable. Thus, HClO solution can be used as a disinfectant for SARS-CoV-2.