For International Workers’ Day: Special Focus on Essential Workers

Detection, Burden, and Impact


Prevalence and clinical profile of severe acute respiratory syndrome coronavirus 2 infection among farmworkers, California, USA, June–November 2020. Lewnard et al. Emerging Infectious Diseases (March 3, 2021).

Key findings:

  • Clinical surveillance found 28.5% (95% CI 20.1-37.4%) higher probability of SARS-CoV-2 infection among farmworkers (22.1%) compared with other adults from the same communities (17.2%), between June 15 and November 30, 2020 (Figure).
  • Among farmworkers in a cross-sectional study, prevalence of current infection was 27.7% in those reporting >= 1 COVID-19 symptom in the prior 2 weeks compared with 7.2% in those without symptoms (adjusted OR 4.16; 95% CI 2.85-6.06).

Methods: Clinical surveillance of SARS-CoV-2 infection based on oropharyngeal swabs at a community and migrant health center in Monterey County, California (6,864 farmworkers and 7,305 other adults in the same communities). A cross-sectional study of farmworkers (n = 1,115) recruited at clinic visit and through outreach assessed for SARS-CoV-2 infection and SARS-CoV-2 symptoms. Limitations: Results not generalizable to all farmworkers.

Implications: SARS-CoV-2 vaccination and prevention efforts should prioritize farmworkers, who may be disproportionately impacted.



Chart showing positive cases among farmworkers and other adults in the community

Note: Adapted from Lewnard et al. Proportion of positive SARS-CoV-2 positive cases among farmworkers and other adults in the same communities. Shading: 95% CIs. Vertical line: start of cross-sectional study. Licensed under CC-BY-NC-ND.

Symptoms of anxiety, burnout, and PTSD and the mitigation effect of serologic testing in emergency department personnel during the COVID-19 pandemic.external icon Rodriguez et al. Annals of Emergency Medicine (February 4, 2021).

Key findings:

  • 46% of emergency department (ED) personnel (N = 1,606) reported symptoms of emotional exhaustion and burnout.
  • 308 (19.2%; 95% CI, 17.3%-21.1%) screened positive at baseline for increased risk of post-traumatic stress disorder (PTSD) by self-reporting symptoms such as having nightmares, avoiding triggers, and feeling on edge (Figure).
    • Female respondents were more likely than males to report symptoms consistent with PTSD (odds ratio [OR] 2.03, 95% CI 1.49-2.78).
  • Among respondents to both baseline and follow-up surveys, fewer personnel screened positive for PTSD risk following SARS-CoV-2 serological testing (reduction 6.5%; 95% CI 4.6%-8.5%).
    • A positive serology test was associated with decreased anxiety (OR 2.83, 95% CI 1.28-6.25).

Methods: Prospective cohort study across 20 EDs in 15 states. Standardized questionnaires were administered, including a screening instrument for PTSD based on the Diagnostic and Statistical Manual of Mental Disorders 5th Edition (DSM-5), at baseline with follow-up ~3 weeks after testing for antibodies to SARS-CoV-2. Limitations: Short follow-up period; lack of control group.

Implications: PTSD symptoms were prevalent among ED staff and were compounded by the uncertainty of their SARS-CoV-2 status. Mitigation strategies and increased SARS-CoV-2 testing may reduce PTSD risk.



Bar chart showing responses to PTSD questionnaire

Note: Adapted from Rodriguez et al. ED personnel responses to the DSM-5 PTSD screening instrument. May to July 2020: the proportion reporting “yes” to experiencing each symptom in the week prior to the baseline and follow-up surveys administered after serological testing for SARS-CoV-2 antibodies. Permission request in process.

Prevalence of SARS-CoV-2 antibodies among market and city bus depot workers in Lima, Peruexternal icon. Tovar et al. Clinical Infectious Diseases (April 21, 2021).

Key findings:

  • SARS-CoV-2 antibody positivity ranged from 27% to 73% in market workers at 8 different markets.
  • SARS-CoV-2 antibody positivity was 11%, 32% and 47% among workers at 3 bus depots.
    • Antibody positivity among bus drivers was 8%, 27%, and 42% at the corresponding depots.

Methods: Day-long SARS-CoV-2 antibody testing campaigns were conducted at 8 markets and 3 bus depots between June 5 and July 18, 2020. Participating market workers (n = 1,285) and bus depot workers (n = 488) received rapid SARS-CoV-2 antibody testing using the Standard Q COVID-19 IgG/IgM Duo. Prevalence of antibody positivity (combined IgG/IgM) was reported. Limitation: Sampling from the workplace can introduce healthy worker bias potentially underestimating past (or current) SARS-CoV-2 infection.

Implications: High prevalence of SARS-CoV-2 infection among market and bus depot workers suggests a critical need for prioritizing frontline workers for vaccination.



A disproportionate epidemic: COVID-19 cases and deaths among essential workers in Toronto, Canada.external icon Rao et al. medRxiv (March 11, 2021).

Key finding:

  • Cumulative per capita cases and deaths were 3.3-fold and 2.5-fold higher, respectively, in neighborhoods with the highest proportion of essential workers compared with neighborhoods with the lowest concentration of essential workers (Figure).

Methods: COVID-19 cases (n = 74,477) and deaths (n = 2,319) between January 23, 2020 and January 24, 2021, in different Toronto neighborhoods compared by proportion of population (in tertiles) that were essential workers (including those in health, food, agriculture, transportation and manufacturing) based on census data. Limitations: Lack of generalizability of results.

Implications: Vaccination is needed to reduce COVID-19 case and death burden among essential workers; community-based interventions targeting neighborhoods with high proportions of essential workers may help reach this population.


Charts showing per-capita COVID-19 cases and deaths in neighborhoods with levels of essential workers

Note: Adapted from Rao et al. Cumulative per-capita COVID-19 cases and deaths by neighborhood-level proportion of essential workers. Essential worker proportions in neighborhoods were stratified by tertiles: Stratum 1 (27.8%; 95% CI 23.4-31.5), Stratum 2 (44.7%; 95% CI 40.0-50.0), Stratum 3 (62.9%; 95% CI 58.4%-68.0). Deaths are 7-day rolling averages. Data do not include residents of long-term care homes. Licensed under CC-BY-NC-ND 4.0.

Excess mortality associated with the COVID-19 pandemic among Californians 18-65 years of age, by occupational sector and occupation, March through October 2020external icon. Chen et al. medRxiv (January 22, 2021).

Key findings:

  • Compared with prior to the pandemic, working-age Californians experienced 22% increased risk of mortality between March and October 2020.
    • Increased mortality was seen among Asian adults (risk ratio [RR] 1.18, 95% CI 1.14-1.23), Black adults (RR 1.28, 95% CI 1.24-1.33), Latino adults (RR 1.36, 95% CI 1.29-1.44) and White adults (RR 1.06 95% CI 1.02-1.12).
  • Increased mortality was seen across all sectors (RR 1.22, 95% CI 1.20-1.24) and was highest for essential workers in food/agriculture (RR 1.39, 95% CI 1.29-1.44) and transportation/logistics (RR 1.28, 95% CI 1.24-1.33) (Figure).

Methods: Death certificates were obtained from the California Department of Health for all deaths occurring on or after January 1, 2016. For decedents aged 18 to 65, occupations were categorized into 9 groups: facilities, food/agriculture, government/community, health/emergency, manufacturing, retail, transportation/logistics, not essential, and unemployed/missing. Excess deaths from March to October 2020 were recorded overall and for each sector. Limitations: Primary occupation on the death certificate may not match the individual’s most recent occupation; misclassification of occupation on death certificates due to broad categories or inaccurate reports.

Implications: In-person essential work may facilitate SARS-CoV-2 transmission and should be addressed through strict enforcement of health orders in workplace settings, protection of in-person workers, and prioritization of vaccine distribution.


Charts showing risk ratios for death by occupational sector

Note: Adapted from Chen et al. Risk ratios for death among Californians 18-65 years of age, by occupational sector, March through October 2020. The dashed vertical lines mark boundaries between phases of California’s major pandemic policies, lagged to acknowledge time from policy decisions to infection and death. The first phase corresponds to a period of sheltering in place, while the second phase corresponds to a period of reopening. Dashed horizontal line denotes RR 1. Used by permission of authors.

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