The effect of salt on the interaction between contact surfaces and COVID-19 droplets

Fomite transmission through contact surfaces is implicated as an important transmission route for viral pathogens. For COVID-19, the role of fomite transmission through surfaces in the recent outbreak is not clear yet and leads to wide debating. In particular, the effect of the Covid-19 droplet composition, such as salinity, on the transmission at contact surfaces is unknown. Here we use molecular dynamics to investigate the interaction between Covid-19 in droplets of varied salinity and hydrophobic/hydrophilic surfaces. We choose cellulose membrane as the hydrophilic surface and graphite as the hydrophobic surface. Our results show that Covid-19 spike protein interacts more strongly with graphite than with cellulose membrane, and both interactions are reduced at increased salinity. We attribute the reduction in interaction to the screening effect. The research provides sheds light on the factors influencing the fomite transmission of Covid-19 via contact surfaces and the potential of viral transmission in different environment.