Transmission risk of viruses in large mucosalivary droplets on the surface of objects: A time-based analysis

Abstract

The novel human coronavirus SARS-CoV-2 has been responsible for a worldwide pandemic. Although media transmission through contaminated surfaces is one of the most recognized ways of transmission, the study on the number and viability of viruses surviving on a surface after leaving the host represents a “blind spot” in current research. In this paper we have reviewed studies on the physical process of droplet evaporation on media surfaces, and analyzed the recent literature related to experiments on the decay of the viral concentration and infectious activity of SARS-CoV-2 and other viruses on those surface and in the air. The huge differences in the risk of media transmission of large saliva and sputum droplets were analyzed in terms of time elapsed. Due to the rapid decrease of water content in the evaporated droplets and the increased concentration of each component, the living environment of the virus tended to deteriorate sharply, and virus concentration plummeted within a few minutes. Although a virus can be detected in a matter of hours, tens of hours, or days, the risk of transmission is negligible compared to when it first left the host. This study suggests that the key to prevention and control is to start from the source, the earlier the better. It is extremely important to develop good public health habits, wear masks, and wash hands frequently. That said, excessive disinfection and sterilization of surfaces during a later period may have adverse effects.

The Commitment of Nineveh Governorate Residents to the Precautionary Measures against Global 2019 Pandemic and Dermatological Affection of Precautions

“…COVID-19 infects the upper and lower part of respiratory tract mucosa, while conjunctiva with the optic canal has the lowest risk of transmission. The incubation period has been estimated to be 14 days on average, while most of the cases show symptoms in 4 to 5 days from exposure and can be infected with mild or even no symptoms [ 9 , 10 ].…”

Porous surfaces: stability and recovery of coronaviruses

“…Desiccation may lead to the viral lipid envelope undergoing phase changes and oxidation, and Maillard reactions may occur within proteins, rendering the virus noninfectious. Changes in pH and salt concentration occurring as water droplets evaporate also contribute to viral inactivation [32,88,89]. This is reflected in previously reported inactivation kinetics of coronaviruses, with a slower initial reduction in viral titre during evaporation followed by a more rapid decline as solutes become more concentrated; this is exemplified by SARS-CoV-2 (5 log 10 TCID 50 ml −1 ) remaining stable on polystyrene for 4 h during the evaporation phase, followed by a decline in viral titre, with around 1 log 10 remaining at 24 h [90].…”

The RNA Interference Effector Protein Argonaute 2 Functions as a Restriction Factor Against SARS-CoV-2

“…This betacoronavirus is transmitted with high efficiency primarily through respiratory aerosols between humans and rapidly establishes infection shortly after exposure. 2 , 3 , 4 Fortunately, the development of vaccines and direct-acting antivirals (reviewed in 5 , 6 ) has reduced the burden of disease in many countries. However, with the continuous emergence of variants of concern, the effectiveness of current vaccines and monoclonal antibodies that were designed against earlier strains of SARS-CoV-2, are significantly lower (reviewed in 7 , 8 ).…”