Community Transmission of SARS-CoV-2 by Fomites: 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 contaminated surfaces and to evaluate the effectiveness of hand and surface disinfection as potential interventions. The risks posed by contacting surfaces in communities are low (average of the median risks 1.6×10−4 - 5.6×10−9) for community infection prevalence rates ranging from 0.2-5%. Hand disinfection substantially reduces relative risks of transmission independently of the disease’s prevalence and the frequency of contact, even with low (25% of people) or moderate (50% of people) compliance. 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.

Longitudinal monitoring of SARS-CoV-2 RNA on high-touch surfaces in a community setting

“…We estimated the risk of COVID-19 infection from touching a contaminated surface using a quantitative microbial risk assessment (QMRA). 46 Infection risks ranged from 2 in 10 million to 4 in 10 thousand (mean=6.5×10 −5 , median=2.2×10 −6 ). The majority of our positive samples were not quantifiable by qPCR and were therefore treated as the theoretical qPCR limit of detection (LOD) for this analysis.…”

“…For future work, the number of touches since last cleaning may be a more relevant metric to consider for SARS-CoV-2 RNA detection on surfaces. 7…”

“…Risks from single hand-to-surface followed by hand-to-face contacts were estimated using the Quantitative Microbial Risk Assessment framework. 7 The Monte Carlo Method ( n =50,000 simulations) was used to incorporate the variability and uncertainty of the input parameters. Probability distributions for each parameter were obtained from published scientific literature or from this paper (Table S10).…”

Knowledge, attitudes, and practices around hand drying in public bathrooms during the COVID-19 pandemic in the United States

“…The data of this survey suggest that the primary concern for respondents in selecting hand drying methods in public bathrooms during the pandemic may be avoiding contacting SARS-CoV-2 on surfaces. As studies to date have found low risk of SARS-CoV-2 transmission from fomites 8 , 9 , the public could benefit from targeted handwashing messaging highlighting this low relative transmission risk.…”

Nanotechnology-Based Self-Sterilizing Surfaces and Their Potential in Combating COVID-19

“…The RNA can remain in place for a few hours to a few days under ambient conditions. The presence of moderate SARS-CoV-2 protein content in respiratory droplets discharged by infected individuals while sneezing or coughing increases the chances of virus survival on the surfaces of contaminated fomites [ 1 ]. However, the survival time of the virus on fomites depends on temperature, humidity, virus inoculum shed on the inanimate surface and nature of the surface material.…”