Taiko Pharmaceutical Co., Ltd. based in Osaka, Japan, hereby announced that long-lasting chlorine dioxide (ClO2) aqueous solution (*1) inactivated over 99.99% of SARS-CoV-2 (COVID-19 Virus), including its Alpha and Gamma variants (*2), in a test conducted in collaboration with Kitasato Institute/Kitasato University in Tokyo, Japan.

SARS-CoV-2 strains were mixed with Taiko Pharmaceutical's long-lasting ClO2 aqueous solution (*1) at the ratio of 1:19 (154 ppm (*3) in aqueous solution remained active for three years' storage) and the infectivity titer was determined by the plaque assay (*5) at 10 sec and 60 sec using TMPRSS2-expressing Vero E6 cells (*4). The results revealed that the ClO2 aqueous solution inactivated over 99.99% of SARS-CoV-2, including the two variant strains.

The Alpha and Gamma variants of SARS-CoV-2 contain N501Y (*6) and E484K (*6) mutation, respectively, and these were suggested to affect, respectively, the infection/transmission potency, and antigenic drift. Currently, worldwide dissemination of the N501Y variant (*7, 8) has been confirmed.

A study reported that ClO2 denatures the spike protein on the surface of SARS-CoV-2 and inhibits its binding to the human ACE2 receptor (*9). The current study adds invaluable information for the effectiveness of long-lasting ClO2 aqueous solution in disinfecting the coronaviruses.

The pandemic dissemination of the novel coronavirus infectious disease (COVID-19) has seriously damaged the human society, threatening millions of human lives. Strategies to combat COVID-19 may be to develop vaccines to establish the herd immunity, effective drugs and disinfectants to inactivate the viruses.