Inactivation of human coronaviruses using an automated room disinfection device

The emergence of more virulent and epidemic strains of viruses, especially with the current COVID-19 pandemic, makes it more important than ever to improve methods of decontamination. The use of vapour dispersion devices or “foggers” have played a critical role in rapidly applying disinfectants over large areas or complex surfaces to prevent the spread of pathogens. The objective of this study was to evaluate the potential of on-demand production of chlorine species to inactivate human coronaviruses. The commercial prototype disinfection unit was provided by Unipolar Water Technologies. The Unipolar device generates active chlorine species using an electrochemical reaction and dispenses the disinfectant vapour onto surfaces with an aspirator. The minimum effective concentration and exposure time of disinfectant were evaluated on human hepatoma (Huh7) cells using 50% tissue culture infectious dose (TCID50) assay and human coronavirus 229E (HCoV-229E), a surrogate for pathogenic human coronaviruses. We showed that chlorine species generated in the Unipolar device inactivates HCoV-229E at ≥ 400 parts per million active chlorine concentration with a 5 min exposure time. Importantly, no toxic effect was observed on Huh7 cells for any of the active chlorine concentrations and contact times tested.