Maleeka singh, University of Guelph; Lawrence Goodridge, University of Guelph; Maria G. Corradini, University of Guelph; Robert Hanner, University of Guelph, and Steven Newmaster, University of Guelph
A recent study from the University of Guelph looked at the risk of exposure to COVID-19 from high-touch surfaces inside grocery stores, and found the risk to be low if physical distancing guidelines and recommended cleaning protocols are followed.
SARS-CoV-2 spreads mainly through direct personal contact, respiratory droplets and body fluids. Recent evidence suggests that indirect transmissionThat is, getting infected by touching inanimate objects or surfaces (fomites) that have come into contact with the virus and then touching your eyes, nose, or mouth, is low but feasible.
When lockdown and quarantine protocols restricted activities, concerns about transmission were channeled into spaces that the public could still visit, such as retail food stores. In these settings, there were concerns about the possible transfer of the virus to clients through high-touch surfaces. Information on the presence, survival and infectivity of SARS-CoV-2, the virus that causes COVID-19, on surfaces was limited, particularly outside of laboratory settings.
Select and test surfaces
We tested 957 samples at four Ontario food retailers over a period of one month, during the second wave of the virus. Due to the reported survival of the SARS-CoV-2 virus on various surfaces, we tested a variety of high-contact surface areas accessible to both employees and customers.
The presence of SARS-CoV-2 has been reported on surfaces in environments with high viral loads, such as hospital wards and patient rooms. Viral persistence and the ability to remain active depend on numerous factors, such as air flow, temperature, and relative humidity within an indoor facility.
The type of material the virus is in contact with can also affect persistence. Studies have found that SARS-CoV-2 was viable for four hours on copper, 24 hours on cardboard and 72 hours on plastic and stainless steel. Another coronavirus, the human coronavirus strain HCoV-229E, which causes common cold symptoms, could survive on various surfaces such as metal, glass or plastic for two hours to nine days. Temperatures between 30-40 C reduced viral persistence and survival.
Based on these data, high-touch surface areas in retail stores were identified in four zones: the pay station, the deli counter, the refrigerated food section, and carts and baskets, as well as in a variety of types. of surfaces, including glass and plexiglass. partitions, metal bumpers, plastic and metal handles.
Samples were collected in the store prior to daily operations and at the end of the workday to assess the possible contribution of the public to surface contamination. The collected samples were stored in a cooler and transported for further processing and detection of the viral RNA. A commercially available detection system and reagent kit approved by Health Canada for SARS-CoV-2 environmental testing was used to assess the presence or absence of viral RNA.
Presence of SARS-CoV-2 on selected surfaces
This study found that regardless of the location of the store (urban or suburban), the day or time of sampling, the location of the surface within the store, or the material on the surface, all samples were negative for RNA from the store. SARS-CoV-2, which means that the values were below the detection limit of the method, which was also validated by control tests.
These results suggest that the risk of exposure from high-touch surfaces within a grocery store is low. This depends on retail stores enforcing and implementing physical distancing measures, regular disinfection routines, and systematic monitoring of the health of store personnel.
These results emphasize the importance of preventive measures to reduce the likelihood of finding SARS-CoV-2 on surfaces that are commonly found and frequently touched in retail stores. This finding is consistent with a recent study on the presence of SARS-CoV-2 in inanimate objects in hospitals. The study found that transmission of the virus through fomites unlikely if cleaning procedures and precautions are maintained.
Next steps: So what?
We believe that wearing masks, maintaining physical detachment, and cleaning and disinfecting contact surfaces significantly minimize the risk of transmission from surfaces in grocery stores to humans. These measures should persist even after vaccines are administered because it is not known how infectious the new emerging variants are and the extent of vaccination varies from place to place. It may be that the variants are less susceptible to disinfection or that they are more easily transmitted.
As it may not be possible to know the number of people infected in stores, the use of personal protective equipment and improved cleaning procedures may be required to ensure that future variants do not cause unforeseen problems.
Maleeka singh, PhD student, Food sciences, University of Guelph; Lawrence Goodridge, Professor, food safety, University of Guelph; Maria G. Corradini, Associate Professor – Arrell Chair of Food Quality, University of Guelph; Robert Hanner, Professor, Department of Integrative Biology, University of Guelph, and Steven Newmaster, Professor, Department of Integrative Biology, University of Guelph