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Short report
SARS-CoV-2 antibody seroprevalence among firefighters in Orange County, California
  1. Verónica Vieira1,2,
  2. Ian W Tang1,
  3. Scott Bartell1,2,
  4. Matthew Zahn3,
  5. Marion Joseph Fedoruk1,2
  1. 1Department of Environmental and Occupational Health, University of California Irvine Susan and Henry Samueli College of Health Sciences, Irvine, California, USA
  2. 2University of California Irvine Center for Occupational and Environmental Health, Irvine, California, USA
  3. 3Orange County Health Care Agency, Santa Ana, California, USA
  1. Correspondence to Dr Verónica Vieira, Department of Environmental and Occupational Health, University of California Irvine College of Health Sciences, Irvine, California, USA; vvieira{at}uci.edu

Abstract

Objectives We conducted serological SARS-CoV-2 antibody testing from October to November 2020 to estimate the SARS-CoV-2 seroprevalence among firefighters/paramedics in Orange County (OC), California.

Methods OC firefighters employed at the time of the surveillance activity were invited to participate in a voluntary survey that collected demographic, occupational and previous COVID-19 testing data, and a SARS-CoV-2 immunoglobulin (Ig)G antibody blood test. We collected venous blood samples using mobile phlebotomy teams that travelled to individual fire stations, in coordination with an annual tuberculosis testing campaign for firefighters employed by OC Fire Authority (OCFA), and independently for firefighters employed by cities. We estimated seroprevalence and assessed several potential predictors of seropositivity.

Results The seroprevalence was 5.3% among 923 OCFA personnel tested, with 92.2% participating. Among firefighters self-reporting a previous positive COVID-19 antibody or PCR test result, twenty-one (37%) did not have positive IgG tests in the current serosurvey. There were no statistically significant differences in demographic characteristics between cases and non-cases. Work city was a significant predictor of case status (p=0.015). Seroprevalence (4.8%) was similar when aggregated across seven city fire departments (42%–65% participation). In total, 1486°C fire personnel were tested.

Conclusion Using a strong serosurvey design and large firefighter cohort, we observed a SARS-CoV-2 IgG seroprevalence of 5.3%. The seroprevalence among OC firefighters in October 2020 was lower than the general county population estimated seroprevalence (11.5%) in August. The difference may be due in part to safety measures taken by OC fire departments at the start of the pandemic, as well as differences in antibody test methods and/or duration of antibody response.

  • firefighters

Data availability statement

Data are available upon reasonable request. Data from this study are available on request by sending an email message to the corresponding author, Dr Verónica Vieira (vvieira@uci.edu).

This article is made freely available for personal use in accordance with BMJ’s website terms and conditions for the duration of the covid-19 pandemic or until otherwise determined by BMJ. You may use, download and print the article for any lawful, non-commercial purpose (including text and data mining) provided that all copyright notices and trade marks are retained.

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Data availability statement

Data are available upon reasonable request. Data from this study are available on request by sending an email message to the corresponding author, Dr Verónica Vieira (vvieira@uci.edu).

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Footnotes

  • Contributors All authors contributed to the research design and manuscript development. VV, SB and IWT completed data collection.

  • Funding This surveillance activity was supported by the Orange County Healthcare Agency.

  • Competing interests None declared.

  • Provenance and peer review Not commissioned; externally peer reviewed.