Controlling risk of SARS-CoV-2 infection in essential workers of enclosed food manufacturing facilities

Sobolik, Julia S.; Sajewski, Elizabeth T.; Jaykus, Lee-Ann; Cooper, D. Kane; Lopman, Ben A.; Kraay, Alicia NM.; Ryan, P. Barry; Leon, Juan S.

The SARS-CoV-2 global pandemic poses significant health risks to workers who are essential to maintaining the food supply chain. Using a quantitative risk assessment model, this study characterized the impact of risk reduction strategies for controlling SARS-CoV-2 transmission (droplet, aerosol, fomite-mediated) among front-line workers in a representative enclosed food manufacturing facility. We simulated: 1) individual and cumulative SARS-CoV-2 infection risks from close contact (droplet and aerosols at 1–3m), aerosol, and fomite-mediated exposures to a susceptible worker following exposure to an infected worker during an 8h-shift; and 2) the relative reduction in SARS-CoV-2 infection risk attributed to infection control interventions (physical distancing, mask use, ventilation, surface disinfection, hand hygiene). Without mitigation measures, the SARS-CoV-2 infection risk was largest for close contact (droplet and aerosol) at 1m (0.96, 95%CI: 0.67–1.0). In comparison, risk associated with fomite (0.26, 95%CI: 0.10–0.56) or aerosol exposure alone (0.05, 95%CI: 0.01–0.13) at 1m distance was substantially lower (73–95%). At 1m, droplet transmission predominated over aerosol and fomite-mediated transmission, however, this changed by 3m, with aerosols comprising the majority of the exposure dose. Increasing physical distancing reduced risk by 84% (1 to 2m) and 91% (1 to 3m). Universal mask use reduced infection risk by 52–88%, depending on mask type. Increasing ventilation (from 0.1 to 2–8 air changes/hour) resulted in risk reductions of 14–54% (1m) and 55–85% (2m). Combining these strategies, together with handwashing and surface disinfection, resulted in <1% infection risk. Current industry SARS-CoV-2 risk reduction strategies, particularly when bundled, provide significant protection to essential food workers.