Research on the Persistence of Antibacterial and Antiviral Effects after Handwashing with Hand Soap

Abstract

The importance of handwashing has become widespread among consumers due to the increased awareness of hygiene following the spread of COVID-19 and awareness-raising activities by the government. However, as a result of a consumer survey, we confirmed that people want to know the antibacterial and antiviral sustainability after handwashing. In this study, we set up a model experimental system assuming the risk of contamination after handwashing, and measured the antibacterial and antiviral effects of different surfactants. As a result of our investigation, the number of viable bacteria was high on public doorknobs and the frequency of touching them was also high. Therefore, assuming the behavior of touching a doorknob four times an hour, we measured the antibacterial and antiviral effects by quantifying the amount of remaining bacteria or viruses when the bacterial or viral solution was applied to the washed model skin every 20 min. The results showed that washing with fatty acid salts decreased the residual amount of bacteria and viruses even after repeated applications, suggesting that the antibacterial and antiviral effects were highly sustained. We consider both deactivating performance and the remaining of surfactant may affect the persistence of antibacterial and antiviral effects.