Fomite Transmission, Physicochemical Origin of Virus-Surface Interactions, and Disinfection Strategies for Enveloped Viruses with Applications to SARS-CoV-2

Abstract

Inanimate objects or surfaces contaminated with infectious agents, referred to as fomites, play an important role in the spread of viruses, including SARS-CoV-2, the virus responsible for the COVID-19 pandemic. The long persistence of viruses (hours to days) on surfaces calls for an urgent need for effective surface disinfection strategies to intercept virus transmission and the spread of diseases. Elucidating the physicochemical processes and surface science underlying the adsorption and transfer of virus between surfaces, as well as their inactivation, is important for understanding how diseases are transmitted and for developing effective intervention strategies. This review summarizes the current knowledge and underlying physicochemical processes of virus transmission, in particular via fomites, and common disinfection approaches. Gaps in knowledge and the areas in need of further research are also identified. The review focuses on SARS-CoV-2, but discussion of related viruses is included to provide a more comprehensive review given that much remains unknown about SARS-CoV-2. Our aim is that this review will provide a broad survey of the issues involved in fomite transmission and intervention to a wide range of readers to better enable them to take on the open research challenges.

Figure 1

(a) Respiratory droplets and aerosol particles produced by an infected host during coughing/sneezing, talking, or exhaling can infect fomites or another individual directly. Droplets settle and adsorb onto fomites, while aerosol particles can remain suspended in air for minutes to hours.^, (b) Indirect fomite-mediated transmission to a new human host occurs through contact with the fomite and subsequent contact with regions through which a virus can enter the body. Contact times can range from ∼1 to 50 s. Virus particles can also be transferred to a surface via touch from contaminated skin (blue arrows).

Figure 2

Droplet settling time from a height of 3 m was approximated based on its terminal velocity. In this approximation, settling timescales with the second power of droplet diameter and the air around the droplet is assumed to be stagnant. We generated this plot using published data.

Figure 3

Diagram summarizing components contributing to XDLVO-based interactions between a virus and a surface. Ionizing residues on viral amino acids interact with surface hydroxyls groups on an adsorbing surface. The Gouy layer forms from a local imbalance in charge concentration. These long-range electrostatic forces are attractive or repulsive based on the charges on the virus and the surface. Apolar hydrophobic groups on the virus and surface exhibit shorter-range interactions. The complex dielectric susceptibility (ε) mismatch of the virus, media, and solid surface drives van der Waals interactions.

Figure 4

Viral structures targeted by different disinfectants. Symbol abbreviations: +, light damage; ++, moderate damage; +++, severe damage; −, no damage; ?, uncertain/debated. Chemical abbreviations: ClO₂, chlorine dioxide; EtOH, ethanol; IPA, isopropanol; H₂O₂, hydrogen peroxide; FA, formaldehyde; GTA, glutaraldehyde. References: heat,^,, UV light,^,− chlorines,^, EtOH and IPA, H₂O_2, surfactants, phenolics, FA and GTA,^, and singlet oxygen.^,,