Is your supermarket a COVID-19 hotspot?

Of 104 workers in a supermarket in the Boston area, 20% had positive virus tests for SARS-CoV-2, three-quarters of which were asymptomatic, researchers said.

An adapted analysis found that employees with direct customer exposure tested positive five times more often, albeit with a broad confidence interval (aOR 5.1, 95% CI 1.1-24.8), reported Dr. Justin Yang of Harvard TH Chan School of Public Health in Boston and colleagues in Occupational and environmental medicine.

In addition, the prevalence of anxiety among workers was 24%, with a depression prevalence of 8%.

Yang’s group found that key workers such as first responders and retailers cannot participate in risk reduction strategies and therefore have a higher potential risk of exposure. Not only that, but “they can become a major source of transmission for the community they serve.”

While much of the research has focused on health care, very few looked at other key workers. While previous studies reported SARS-CoV-2 infections in supermarkets, “no study has looked at SARS-CoV-2 exposure risk or psychological stress in key food retailers.”

The supermarket employees analyzed in the current study were clinically evaluated for three days at the beginning of May 2020 and swabbed nasopharyngeally. Demographic information, SARS-CoV-2-related exposure, symptoms within the past 1-2 weeks, use of personal protective equipment, and mental health surveys were addressed on a paper questionnaire prior to screening. Tools for mental health screening included the patient health questionnaire 9 and general anxiety disorder 7.

The average age of the employees was 49 years, 47% were women and 62% were non-Caucasian minorities. Of the 21 employees who tested positive for SARS-CoV-2, 91% had a job with significant direct customer exposure compared to 59% of SARS-CoV-2 negative employees (P.= 0.009). There was no statistical difference in protective behaviors such as social distancing, use of masks and / or gloves, avoidance of public transport or shared journeys.

About half of workers with anxiety reported being able to consistently practice social distancing at work, compared with 76% without anxiety (P.= 0,009).

Workers who tested positive for depression were less consistent in practicing social distancing and more likely to commute using public transit or shared trips, the authors found. In fact, the ability to consistently practice social distancing at work has been inversely linked to both anxiety and depression.

Yang and colleagues found that the infection rate was significantly higher than in the surrounding communities, where rates were all below 2%.

The limitations of the study include the small sample size and unmeasured confounders, the cross-sectional design (from which the cause cannot be deduced) and most of the data other than test results come from a self-reported questionnaire.