Virus stability in evaporating respiratory droplets

COVID-19 has reached a pandemic level worldwide, becoming the greatest concern of the scientific community to unveil the biological and physical phenomena of viral transmission. However, the exact contribution of respiratory droplets to the transmission of respiratory diseases is still unclear. Here we aim to understand the influence of evaporation on the stability of a virus on a respiratory droplet. We observe the evaporation dynamics of sessile droplets from pure water and artificial saliva containing nanoparticles with similar size and structure to viruses, as well as visualize the evaporating respiratory droplets with holotomographic microscopy. To explain the acquired experimental data, a physical model is proposed by identifying a relationship between droplet evaporation and virus stability. We believe that this result would be useful to comprehend the virus stability and survivability in surfaces, allowing better safety measurements to control viral transmission through respiratory droplets.