Assessment of antiviral coatings for high-touch surfaces using human coronaviruses HCoV-229E and SARS-CoV-2.

A novel and robust approach to evaluate the antiviral activity of coatings was developed, assessing three commercially available leave-on surface coating products for efficacy against human coronaviruses HCoV-229E and SARS-CoV-2. The assessment is based on three criteria that reflect real-life settings, namely (i) immediate antiviral effect, (ii) effect after repeated cleaning of the coated surface, and (iii) antiviral activity in the presence of organic material. The results showed that only a copper compound-based coating successfully met all three criteria. A quaternary ammonium compound-based coating did not meet the second criterion, and a coating based on reactive oxygen species showed no antiviral effect. Moreover, the study demonstrated that HCoV-229E is a relevant SARS-CoV-2 surrogate for such experiments. This new approach allows to benchmark currently available antiviral coatings and future coating developments to avoid unjustified claims. The deployment of efficient antiviral coatings can offer an additional measure to mitigate the risk of transmission of respiratory viruses such as SARS-CoV-2 or influenza viruses from high-touch surfaces. Importance SARS-CoV-2, the virus responsible for the COVID-19 pandemic, is transmitted mainly by person-to-person through respiratory droplets whilst the contribution of fomite transmission is less important than suspected at the beginning of the pandemic. Nevertheless, antiviral coating solutions can offer an additional measure to mitigate the risk of SARS-CoV-2 transmission from high-touch surfaces. The deployment of antiviral coatings is not new, but what is currently lacking is solid scientific evidence of the efficacy of commercially available self-disinfecting surfaces under real-life conditions. Therefore, we developed a novel, robust approach to evaluate the antiviral activity of such coatings, applying strict quality criteria to three commercially available products to test their efficacy against SARS-CoV-2. We also showed that HCoV-229E is a relevant surrogate for such experiments. Our approach will bring significant benefit to evaluate the effect of coatings also on the survival of non-enveloped viruses, known to be more tolerant to desiccation and disinfectants and for which high-touch surfaces play an important role.