Study population and setting
The study objective was to report the number of COVID-19 cases traced to workplace settings in Utah as determined by the state’s COVID-19 surveillance system. From March 6 to June 5, 2020, 277 COVID-19 outbreaks were reported, representing 1,389 COVID-19 cases out of 11,448 across the state (12%). Workplace outbreaks were defined as having two or more laboratory-confirmed cases within the same 14-day window among coworkers at the same facility. Utah Department of Health (UDOH) investigators collected the addresses and/or business names for all outbreaks and classified them into 20 industry sectors as determined by the North American Industry Classification System (NAICS), as obtained by the Division of Corporations and Commercial Code business registry the Utah state government maintains. Cases per 100,000 workers were calculated using estimates from the 2019 Census Quarterly Workforce Indicators. Race/ethnicity information, hospitalization status, and number of severe outcomes were also collected.
Summary of Main Findings
Of the 277 outbreaks in the state, 210 were linked to workplaces (75.8%), representing 1,389 cases. The most represented industries were manufacturing (20%), construction (15%) and wholesale trade (14%), which made up the majority of cases (806 total cases in these three sectors). The workplace outbreak attack rate was 106.4 cases per 100,000 workers overall, and was highest among manufacturing (339.4 per 100,000 workers) and wholesale trade (377.0 cases per 100,000 workers). Of the 1335 cases with race/ethnic data available, 73% were among Hispanic or Black, Indigenous and people of color (N=970). 85 were admitted to the hospital (6%) and 40 had severe outcomes (3%). The median cases per outbreak was 4, with ranges from 2 to 79 cases. Compared with people in the state 15 years or older, people with workplace-associated COVID-19 tended to be older (41 years on average, compared to 38 years), more likely to identify as Hispanic (56.4% vs. 39.8%), and be male (61.4% vs. 50.6%).
The study used the Utah surveillance system to identify all workplace outbreaks, and were able to report on a number of important sociodemographic disparities with their individual-level information. Additionally, using the population of working age in the state, they were able to examine whether those with workplace-related COVID-19 were getting sick at a higher rate or not, which has important insights for the type of workers being placed most at risk. Additionally, they used lab-confirmed diagnosis of COVID-19, which reduced misclassification in their results (though they do not state what type of lab test was used).
Grouping by industries shows important trends, but further disaggregation for the main categories (e.g., what type of wholesale trade or manufacturing) would given further insight into what conditions may be leading to the increased risk of outbreaks. Additionally, they do not collect temporal trends that may have altered the probability of an outbreak, such as mandatory closures, and may have affected certain industries more than others. If a handful of industries remained closed throughout the study period, then they would have fewer outbreaks regardless of the actual working conditions, and would not be a valid comparison to industries who did not face these closures. Additionally, worker-to-worker transmission could not be confirmed, and outbreaks that had two individuals who were independently infected would still be included in the analysis. Outbreaks in smaller workplaces would also likely be left out of this analysis.
This is one of the largest by-sector workplace analyses in the US that also collected race/ethnicity and age data to further identify populations most at risk for infection.
This review was posted on: 21 September 2020