Community Transmission of SARS-CoV-2 by Surfaces: Risks and Risk Reduction Strategies

Abstract

SARS-CoV-2, the virus responsible for the COVID-19 pandemic, is perceived to be primarily transmitted via person-to-person contact through droplets produced while talking, coughing, and sneezing. Transmission may also occur through other routes, including contaminated surfaces; nevertheless, the role that surfaces have on the spread of the disease remains contested. Here, we use the Quantitative Microbial Risk Assessment framework to examine the risks of community transmission of SARS-CoV-2 through surfaces and to evaluate the effectiveness of hand and surface disinfection as potential interventions. Using conservative assumptions on input parameters of the model (e.g., dose−response relationship, ratio of genome copies to infective virus), the average of the median risks for single hand-to-surface contact followed by hand-to-face contact range from 1.6 × 10 −4 to 5.6 × 10 −9 for modeled prevalence rates of 0.2%−5%. For observed prevalence rates (0.2%, 1%), this corresponds to a low risk of infection (<10 −6 ). Hand disinfection substantially reduces risks of transmission independently of the disease's prevalence and contact frequency. In contrast, the effectiveness of surface disinfection is highly dependent on the prevalence and the frequency of contacts. The work supports the current perception that contaminated surfaces are not a primary mode of transmission of SARS-CoV-2 and affirms the benefits of making hand disinfectants widely available.

A realistic transfer method reveals low risk of SARS-CoV-2 transmission via contaminated euro coins and banknotes

“…Human-to-human transmission of SARS-CoV-2 occurs primarily by respiratory aerosols or droplets and subsequent contact to nasal, oral, or ocular mucosal membranes. Based upon virus stability on surfaces, fomite transmission of SARS-CoV-2 has been considered possible (Chin et al, 2020;van Doremalen et al, 2020;Biryukov et al, 2020;Bueckert et al, 2020;Kwon et al, 2021;Riddell et al, 2020); however, the importance of this route in health care and public settings remains controversial (Goldman 2020;Mondelli et al, 2020;Pitol and Julian 2021). Fomite-based transmission has been proposed to contribute to the spread of other common respiratory pathogens (Kraay et al, 2018;Boone and Gerba 2007).…”

SARS-CoV-2 Detection Rates from Surface Samples Do Not Implicate Public Surfaces as Relevant Sources for Transmission

“…The CDC has recently published a science brief on the possible transmission of SARS-CoV-2 from surfaces and concluded that it is possible for people to be infected through contact with contaminated surfaces or objects (fomites), but the risk is generally considered to be low [67]. Based on different quantitative microbial risk assessments, it was considered to be generally less than 1 in 10,000 [55,68]. Under low viral bioburden conditions (<1 genome copy per cm 2 ), it was described to be below 1:1,000,000 [69].…”

Human Coronaviruses Do Not Transfer Efficiently between Surfaces in the Absence of Organic Materials

“…Another example was from Guanzhong, China, where it was determined that a cluster of familial cases was initially caused by an indirect infection of one family member who came into contact with a snot-contaminated elevator button [15]. In contrast to this, however, reports and studies have been published that have shown the risk of fomite-mediated transmission of SARS-CoV-2 is likely to be low [16] and other researchers have also suggested that the risk is likely exaggerated [17,18].…”