Top 5 Takeaways

  1. Higher Incidence and Mortality in Public Transportation: Public transportation industries in California had 1.5 times the cumulative COVID-19 outbreak incidence and mortality rates compared to all industries, with the bus and urban transit industry experiencing rates 5.2 times and 1.8 times as high, respectively.
  2. Need for Priority in Prevention Strategies: The elevated risk highlights the need for prioritizing public transportation workers for COVID-19 prevention strategies, including vaccination and enhanced workplace protection measures.
  3. Significant Findings from the Study: The study identified 340 confirmed COVID-19 outbreaks, 5,641 outbreak-associated cases, and 537 COVID-19–associated deaths among California public transportation industries from January 2020 to May 2022.
  4. Variation Across Industries: While all public transportation industries faced increased risks, notable differences existed among them, with the bus and urban transit industry most affected. The air transportation industry had higher outbreak incidence, possibly reflecting enhanced outbreak identification capabilities.
  5. Implications for Public Health Practice: The findings underscore the importance of targeted intervention and support for public transportation workers to mitigate COVID-19 risks, emphasizing the need for improved workplace safety measures.

Original Article Author and Citation

Corresponding Author

Amy Heinzerling,

Suggested Citation

Heinzerling A, Vergara XP, Gebreegziabher E, et al. COVID-19 Outbreaks and Mortality Among Public Transportation Workers — California, January 2020–May 2022. MMWR Morb Mortal Wkly Rep 2022;71:1052–1056.DOI:


This MMWR article details the heightened COVID-19 outbreak incidence and mortality rates among public transportation workers in California from January 2020 to May 2022. It underscores the disproportionate impact of COVID-19 on this workforce compared to all industries statewide, advocating for prioritized prevention strategies.


The California Department of Public Health analyzed confirmed COVID-19 outbreaks and deaths among working-age adults in public transportation industries. Outbreaks were defined based on criteria involving epidemiological links among cases. Mortality analysis was restricted to workers aged 18–64, utilizing state death certificate data matched to COVID-19 case registry records.


The report discusses the elevated risk of COVID-19 exposure and death among public transportation workers, highlighting differences across industries and the impact of workplace conditions. It also notes limitations such as the generalizability of findings and the potential underestimation of 2020 outbreaks.


Public transportation workers are at a heightened risk for COVID-19, necessitating targeted prevention strategies. The report calls for enhanced workplace protections, vaccination efforts, and public health messaging to safeguard this vulnerable worker group.

This has been your booster shot of MMWR Info! Please check back for more MMWR, Public Health, and Programming Tutorial content daily.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes:

<a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>