A recent study published in the journal Food control examines the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in closed industrial facilities to understand the relative reduction in risk attributed to infection control interventions.
The study confirms the current recommendations for key workers in the food industry from the current international (US Occupational Safety and Health Administration) [OSHA], and EU-OSHA, EU-OSHA), domestic (US Food and Drug Administration [FDA], OSHA), and the Food Industry Standard Guideline for the Management of Coronavirus Disease 2019 (COVID-19) and SARS-CoV-2 Transmission in Important Workers in the Food Manufacturing Sector. These include symptom screening, physical distance, mask use, improved surface disinfection and hand washing.
Study: Control of the risk of SARS-CoV-2 infection in major workers at closed food production facilities. Image credit: SeventyFour / Shtuterstock.com
In order to maintain global food supply chains and consumer food security, it is crucial to protect the health of these workers during the ongoing COVID-19 pandemic. However, the relative importance of SARS-CoV-2 transmission, specifically in the food industry, has not been quantified.
Viral transmission of SARS-CoV-2 can occur directly through exposure to infected droplets and aerosol, as well as indirect transmissions by touching contaminated surfaces of fomit.
Upon close contact of less than 2 meters, susceptible individuals can become infected through droplets, which are large virus-containing particles that are more than 100 micrometers (µm) in diameter by respiratory events such as coughing or sneezing.
By comparison, aerosols are droplets, and exposure to these droplets can occur in close contact or at longer distances of up to 9 meters. These particles are excreted during all respiratory events, especially during breathing and speech.
Indirect transmission upon exposure to contaminated fomit surfaces is detected on surfaces in different environments. Previous studies have found that the presence of SARS-CoV-2 remains on fomite surfaces for up to 72 hours. Because food workers share workstations and tactile events occur, it is also important to examine the role of fomit-mediated transmission in food production and processing.
While studies suggest physical distancing, mask, handwashing, and surface disinfection as effective measures against SARS-CoV-2 transmission, no health risks associated with direct and indirect transmission routes have been evaluated. This type of evaluation would provide insight into the effectiveness of infection control strategies in food production facilities.
In this study, the researchers use a stochastic quantitative microbial risk assessment (QMRA) model to quantify the impact of risk reduction measures to control SARS-CoV-2 transmission (droplet, aerosol, fomit-mediated) among significant workers in an indoor fresh fruit- and vegetable factory. The measures addressed in the current study include physical distance, masking, ventilation, surface disinfection, hand hygiene and vaccination.
The structure of the QMRA model varies according to the viral transmission pathways, worker shifts, contact distance (close / far), breathing event, and commonly used infection control interventions. To estimate SARS-CoV-2 infection risks among essential food workers, the authors examined the relative contribution of each transmission route (aerosol, droplets, fomit) with the distance traveled for each size class of expelled infectious particles in 1 hour and cumulative 8-hour SAR exposure. -CoV-2 in closed food production facilities with a coughing infected worker.
The researchers found that the infectious particle spread was affected by the distance at which the droplet transmission contributed with the largest dose of 90% with the dominant transmission state of 1 meter. Close contact aerosols and droplet exposures dominated the risk of infection.
While studying the impact of individual interventions targeting combined risk, the authors showed that the physical distance of 2 meters and above provided the greatest relative reduction in the risk of infection. In addition, physical distance maintained with applied masks resulted in a greater risk reduction compared to when the distance or masks were used alone, except when N95 respirators were used.
Importantly, the researchers found that full vaccination reduced the risk of infection by 92%. In addition, bundled interventions that included physical distance of 2 meters, universal mask wear and at least 2 air changes per hour (ACH), combined with hand washing every hour and surface disinfection twice per minute, were reduced. change the risk to less than 1% for an 8-hour cumulative exposure.
The current study uses mathematical modeling to find that workers in closed food production facilities have a higher risk of SARS-CoV-2 infection from close contact transmission due to exposure to large droplets and small aerosol particles than fomit transmission. Thus, some of the strategies for protecting workers to be adopted include physical distance, universal mask use, and air change in the room followed by surface disinfection to reduce the transfer of fomite and washbasin.
Vaccination is also an effective infection control measure, especially when combined with these existing food industry standards, as it reduced the risk of infection by 92%.
Current work promotes evidence-based support for effective risk reduction strategies currently being implemented by the food industry. While the model here is designed for indoor food production, the researchers suggest that it can be easily adapted to other indoor environments and infectious respiratory pathogens.
- Sobolik, JS, Sajewski, ET, Jaykus, L., et al. (2021). Combating the risk of SARS-CoV-2 infection in major workers at closed food production facilities. Food control. doi: 10.1016 / j.foodcont.2021.108632.