How coronavirus survives for days on surfaces

Area of Science:

• Fluid Dynamics
• Surface Science
• Virology

Background:

• Respiratory droplets containing viruses can remain viable on surfaces for extended periods.
• Previous work showed rapid drying of bulk droplets, contrasting with observed virus survival times.

Purpose of the Study:

• To investigate the mechanism behind prolonged coronavirus survival on surfaces.
• To model the evaporation dynamics of thin liquid films left by respiratory droplets.
• To correlate model predictions with experimental observations of virus decay.

Main Methods:

• Computational modeling of thin liquid film evaporation.
• Incorporation of disjoining and Laplace pressures into the evaporation model.
• Analysis of model sensitivity to initial film thickness, contact angle, and surface type.

Main Results:

• The model predicts nanometer-scale film drying times on the order of hours.
• Drying time is strongly dependent on the initial film thickness.
• Computed film volume decay qualitatively matches experimental virus titer decay.

Conclusions:

• Slow evaporation of residual thin films explains long coronavirus survival times on surfaces.
• The model provides insights into virus viability on solid surfaces under ambient conditions.
• Further examination of surface properties and contact angles can refine understanding of virus persistence.