Workplace
SHORT REPORT Epidemiology of SARS-CoV-2 antibodies among firefighters/paramedics of a US fire department: a cross-sectional study Alberto J Caban-Martinez , 1,2 Natasha Schaefer-Solle, 2,3 Katerina Santiago, 1 Paola Louzado-Feliciano, 1 Angel Brotons, 4 Marco Gonzalez, 4 S. Barry Issenberg, 4 Erin Kobetz 1,2,3
1 Public Health Sciences, University of Miami Miller School of Medicine, Miami, Florida, USA 2 Sylvester Comprehensive Cancer Center, Miami, Florida, USA 3 Medicine, University of Miami School of Medicine, Miami, Florida, USA 4 Gordon Center for Research in Medical Education, University of Miami Miller School of Medicine, Miami, Florida, USA Correspondence to Dr Alberto J Caban-Martinez, Public Health Sciences, University of Miami Miller School of Medicine, Miami, FL 33136, USA; a caban@med.m iami.edu
ABSTRACT Objectives We estimate the point seroprevalence of SARS-CoV-2 antibodies in the frontline firefighter/ paramedic workforce of a South Florida fire department located in the epicentre of a State outbreak. Methods A cross-sectional study design was used to estimate the point seroprevalence of SARS-CoV-2 antibodies using a rapid immunoglobulin (Ig)M-IgG combined point-of-care lateral flow immunoassay among frontline firefighters/paramedics collected over a 2-day period, 16–17 April 2020. Fire department personnel were emailed a survey link assessing COVID-19 symptoms and work exposures the day prior to the scheduled drive-through antibody testing at a designated fire station. Off-duty and on-duty firefighter/paramedic personnel drove through the fire station/training facility in their personal vehicles or on-duty engine/rescue trucks for SARS-CoV-2 antibody testing. Results Among the 203 firefighters/paramedics that make up the fire department workforce, 18 firefighters/ paramedics (8.9%) tested positive for SARS-CoV-2 antibodies, of which 8 firefighters/paramedics (3.9%) were IgG positive only, 8 (3.9%) were IgM positive only and 2 (0.1%) were IgG/IgM positive. The positive predictive value (PPV) of the serological test is estimated to be 33.2% and the negative predictive value is 99.3%. The average number of COVID-19 case contacts (ie, within 6 feet of an infected person (laboratory- confirmed or probable COVID-19 patient) for ≥15 min) experienced by firefighters/paramedics was higher for those with positive serology compared with those with negative (13.3 cases vs 7.31 cases; p=0.022). None of the antibody positive firefighters/paramedics reported receipt of the annual influenza vaccine compared with firefighters/paramedics who tested negative for SARS- CoV-2 antibodies (0.0% vs 21.0%; p=0.027). Conclusion Rapid SARS-CoV-2 IgM-IgG antibody testing documented early-stage and late-stage infection in a firefighter workforce providing insight to a broader medical surveillance project on return to work for firefighters/paramedics. Given the relatively low PPV of the serological test used in this study back in April 2020, caution should be used in interpreting test results.
Key messages
first responders from coronavirus evolved following the first American COVID-19 case and the exposure of at least one firefighter. 1 Among all US jobs, those employed as first responders, that is, firefighters/ paramedics, are at greatest risk for COVID-19 infection, as they can encounter diseases and infec- tions daily and typically work in close proximity to one another and the communities they serve. 2 Many first responders are already under quarantine due to direct exposure with COVID-19 cases, potentially challenging fire department staffing resources and emergency responder workforce responsiveness. 3 While firefighters/paramedics use personal protec- tive equipment (PPE) and engineering controls at work, fire departments are operating in the dark ► ► None of the antibody positive firefighters/ paramedics reported receipt of the annual influenza vaccine compared with firefighters/ paramedics who tested negative for SARS- CoV-2 antibodies (0.0% vs 21.0%; p=0.027). How might this impact on policy or clinical practice in the foreseeable future? ► ► A comprehensive medical surveillance programme for first responders that includes SARS-CoV-2 antibody testing can inform policy for return to work algorithms. What is already known about this subject? ► ► Among all occupations, those employed as first responders, that is, firefighters/paramedics, are at greatest risk for COVID-19 infection, as they can encounter diseases and infections daily and typically work in close proximity to one another and the communities they serve. What are the new findings? ► ► We found the seroprevalence of SARS-CoV-2 antibodies (immunoglobulin (Ig)G only, IgM only or IgG/IgM) estimated in a cross-sectional study of 203 frontline firefighters/paramedics from a municipal fire department was 8.9% of the workforce, of which eight firefighters/ paramedics (3.9%) were IgG positive only, eight (3.9%) were IgM positive only and two (0.1%) were IgG/IgM positive.
Received 7 May 2020 Revised 12 July 2020 Accepted 20 July 2020 Published Online First 6 August 2020
© Author(s) (or their employer(s)) 2020. No
To cite: Caban-Martinez AJ, Schaefer-Solle N, Santiago K, et al . Occup Environ Med 2020; 77 :857–861. commercial re-use. See rights and permissions. Published by BMJ.
INTRODUCTION Key direction from the US Centers for Disease Control and Prevention (CDC) on how to protect
Caban-Martinez AJ, et al . Occup Environ Med 2020; 77 :857–861. doi:10.1136/oemed-2020-106676
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