Evaluation of respiratory virus transmissibility and resilience from fomites: the case of 11 SARS-CoV-2 clinical isolates

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused a global pandemic, significantly impacting social and economic aspects of society. While belonging to the Coronaviridae family, SARS-CoV-2 exhibited unique characteristics that facilitated its widespread transmission and pathogenicity. This study aimed to investigate the molecular characterization and infection kinetics of emerging SARS-CoV-2 variants, focusing on four key virological aspects: viral entry mechanisms, replication dynamics, immune evasion strategies, and surface persistence. We isolated 11 SARS-CoV-2 variants from clinical samples and conducted in vitro studies using Calu-3 cell lines and pseudovirus systems to explore viral entry. Whole-genome sequencing identified mutations linked to increased replication and enhanced immune evasion, particularly through the inhibition of interferon responses. Additionally, persistence studies on common environmental surfaces (copper, aluminum, and plastic) revealed that certain variants, such as G446S, contributed to increased viral stability, suggesting potential for indirect transmission beyond direct person-to-person contact. Furthermore, we evaluated the effectiveness of “green” disinfectants, including tea tree oil and quercetin-based compounds, which demonstrated viral load reductions of over 95% within minutes, outperforming conventional alcohol- and UV-based disinfection methods. Notably, two influenza virus isolates belonging to highly divergent subtypes are sanitized as well while showing different persistence surface profiles compared to SARS-CoV-2. These findings highlight the evolutionary strategies employed by SARS-CoV-2 to ensure transmission, its ability to adapt under selective pressure, and the importance of ongoing surveillance of emerging variants. Moreover, the efficacy of environmentally sustainable disinfectants presents a promising strategy for reducing viral transmission in both clinical and community settings.