**Background:** Meat packing, produce processing, and farm workers have been recognized as having elevated risk for COVID-19, but the specific occupational risk factors driving transmission in these populations remained unclear. The food processing workforce is disproportionately composed of Black and Latinx individuals, and facilities may provide favorable conditions for SARS-CoV-2 transmission including cold temperatures, low humidity, poor ventilation, and close physical proximity. This study aimed to describe SARS-CoV-2 seroprevalence and identify occupational and sociodemographic characteristics associated with prior infection among food processing workers in North Carolina.
**Methods:** The study enrolled 118 adult participants who had worked in a meat packing plant, produce processing facility, or commercial farm in North Carolina for at least two weeks since February 2020. Recruitment occurred through retrospective chart review at a federally qualified health center, flyers, social media, and community organizations. Enrollment visits took place between September and December 2020. Participants completed a questionnaire covering demographics, medical history, workplace and household characteristics, and preventive behaviors. Three biological samples (blood, saliva, and nasal turbinate swab) were collected. Past SARS-CoV-2 infection was assessed using a total Ig SARS-CoV-2 receptor binding domain (RBD) ELISA. For 17 participants unable to provide blood by venipuncture, capillary blood was collected via finger prick and tested using UNscience COVID-19 IgG/IgM rapid detection test strips with confirmation by whole blood ELISA. Statistical analyses included two-sample t-tests, chi-square tests, and unadjusted and adjusted risk ratio analyses using log-binomial models. Adjusted models included age and variables significantly associated with the outcome in unadjusted analyses.
**Key Results:** The overall SARS-CoV-2 seroprevalence was 50.0% (59/118). Seroprevalence was highest among meat packing plant workers (64.6%, 31/48), followed by farm workers (45.0%, 27/60) and produce processing workers (10.0%, 1/10). Demographics were similar across industries: participants were 61.0% female, 94.9% Latinx, with a mean age of 41.9 (±13.2) years. In unadjusted analyses, working in loud environments necessitating yelling to communicate (RR: 1.83, 95% CI: 1.25–2.69), working in cold environments below 16°C (RR: 1.58, 95% CI: 1.12–2.24), and continuing to work despite developing symptoms (RR: 1.63, 95% CI: 1.14–2.32) were significantly associated with SARS-CoV-2 seropositivity. After adjusting for age and working despite symptoms, high noise levels remained significantly associated with a 1.72 times higher risk of seropositivity (95% CI: 1.16–2.55). The association between loud environments and seropositivity persisted in the subset of workers who did not work in cold environments (RR: 1.68, 95% CI: 1.02–2.77). Among seropositive workers, only 49.2% (29/59) reported a known history of COVID-19, compared to 10.2% (6/59) of seronegative workers. Farm workers were significantly less likely than other industry workers to report a history of COVID-19 (22.2% vs. 71.9%, p<0.001). Regular mask wearing was reported by 77.5% of participants, but was not significantly associated with seropositivity.
**Clinical Implications:** This study demonstrates that half of food processing workers in North Carolina had evidence of past SARS-CoV-2 infection by fall 2020, a prevalence over five times higher than the general US population at that time. The high rate of asymptomatic or unrecognized infection (approximately 50% of seropositive workers did not report a known history of COVID-19) underscores the importance of routine surveillance testing in these settings rather than relying on symptom-based screening. The novel finding that high occupational noise levels are strongly associated with SARS-CoV-2 seropositivity suggests that mitigation strategies such as reducing ambient noise, using speakers, optimizing facility engineering, and ensuring consistent mask use could reduce transmission risk. The finding that 13.6% of workers continued working despite developing COVID-19 symptoms highlights the critical need for adequate paid sick leave policies. The disproportionate burden on Latinx workers (94.9% of the study population) reflects broader health disparities affecting underserved and economically disadvantaged communities. These findings remain relevant for future airborne epidemics and for managing ongoing COVID-19 risks given incomplete vaccination rates and emerging variants.