Likelihood of survival of coronavirus in a respiratory droplet deposited on a solid surface

TL;DR

This study models the evaporation and survival of COVID-19 in respiratory droplets on surfaces, analyzing how environmental factors influence virus viability and potential for transmission.

Contribution

It introduces a diffusion-limited evaporation model considering various environmental parameters to predict virus survival in droplets on surfaces.

Findings

Virus survival probability varies with temperature and humidity.

Shear stress inside droplets is insufficient to inactivate the virus.

Weak correlation between droplet drying time and COVID-19 spread rate.

Abstract

We predict and analyze the drying time of respiratory droplets from a COVID-19 infected subject, which is a crucial time to infect another subject. The drying of the droplet is predicted by diffusion-limited evaporation model for a sessile droplet placed on a partially-wetted surface with a pinned contact line. The variation of droplet volume, contact angle, ambient temperature, and humidity are considered. We analyze the chances of the survival of the viruses present in the droplet, based on the lifetime of the droplets in several conditions, and find that the chances of survival of the virus are strongly affected by each of these parameters. The magnitude of shear stress inside the droplet computed using the model is not large enough to obliterate the virus. We also explore the relationship between the drying time of a droplet and the growth rate of the spread of COVID-19 for five different cities, and find that they are weakly correlated.