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

Abstract

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 indoor fresh fruit and vegetable manufacturing facility. We simulated: 1) individual and cumulative SARS-CoV-2 infection risks from close contact (droplet and aerosols at 1–3 m), aerosol, and fomite-mediated exposures to a susceptible worker following exposure to an infected worker during an 8 h-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, vaccination). Without mitigation measures, the SARS-CoV-2 infection risk was largest for close contact (droplet and aerosol) at 1 m (0.96, 5th – 95th percentile: 0.67–1.0). In comparison, risk associated with fomite (0.26, 5th – 95th percentile: 0.10–0.56) or aerosol exposure alone (0.05, 5th – 95th percentile: 0.01–0.13) at 1 m distance was substantially lower (73–95%). At 1 m, droplet transmission predominated over aerosol and fomite-mediated transmission, however, this changed by 3 m, with aerosols comprising the majority of the exposure dose. Increasing physical distancing reduced risk by 84% (1–2 m) and 91% (1–3 m). 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% (1 m) and 55–85% (2 m). Combining these strategies, together with handwashing and surface disinfection, resulted in <1% infection risk. Partial or full vaccination of the susceptible worker resulted in risk reductions of 73–92% (1 m risk range: 0.08–0.26). However, vaccination paired with other interventions (ACH 2, mask use, or distancing) was necessary to achieve infection risks <1%. Current industry SARS-CoV-2 risk reduction strategies, particularly when bundled, provide significant protection to essential food workers.