COVID-19 Surveillance and Vaccination among Non-Healthcare, Non-Congregate Workers in Chicago

BACKGROUND Occupation has been defined as a primary risk factor for SARS-CoV-2 infection, but utility of surveillance practices among non-healthcare, non-congregate workplaces (NHNCW) have not been well-described. Definitions of workers at disproportionate COVID-19 risk and barriers to their vaccination are needed, to inform public health guidance and interventions. METHODS COVID-19 workplace clusters and outbreaks investigated by the Chicago Department of Public Health (March 2020 - May 2022) were described by workplace type, investigation size, and method of identification over time. Logistic regression assessed associations between occupational COVID-19 risk and vaccination status among NHNCW cases reported June 2021-2022, stratified by Pre-and Post-Omicron periods. A survey of Workplace Encouragement for COVID-19 Vaccination in Chicago (WEVax) was administered to workplaces (July – September 2022). Workplace characteristics, coverage rates and barriers to vaccination among employees were described. Frequencies of vaccination encouragement strategies were compared among high vs. lower-coverage workplaces. RESULTS In total, 496 COVID-19 investigations identified 442 clusters (89%) and 54 outbreaks (11%). Frontline essential workplaces comprised 36% before, versus 15% after vaccine eligibility. Case interviewing identified 84% Pre-Omicron, versus 10% Post-Omicron. Over time, offices, bars and restaurants, and less vulnerable city regions became overrepresented. Among 3,763 NHNCW cases, 18–29-year-olds, Latinx and Black-non-Latinx workers were over-represented among higher-risk occupations and unvaccinated Chicagoans. Among 18-29-year-old Pre-Omicron cases, those in higher-risk occupations had 1.5 times the odds of being unvaccinated (95% CI 1.10-2.14). Among 49 WEVax survey respondents, 59% reported coverage rates ≥ 75%; 75% of lower coverage workplaces were in manufacturing and had ˂ 100 employees. Coverage was higher among workplaces requiring vaccination (93% vs. 49%, p=0.03) or verifying vaccination (84% vs. 38%, p=0.07). Businesses reported using strategies to make vaccinations convenient. Concerns about safety, side effects, and other skepticism remain barriers to uptake. CONCLUSIONS Vaccine prioritization reduced COVID-19 burden among highest-risk workplaces, but surveillance methods became less representative. Vaccine promotion among workers in high-risk environments may increase coverage among under-vaccinated demographic groups in Chicago. Vaccine requirement, verification and addressing low vaccine confidence may improve coverage among NHNCW. Future studies should include low-coverage businesses and assess vaccination motivators (not only barriers) among employees.