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Observational Study
. 2023 Feb:64:155-160.
doi: 10.1016/j.ajem.2022.12.012. Epub 2022 Dec 14.

Incidence of unknown COVID-19 infection in a cohort of emergency physicians and advance practice providers

Aaron Nathan Barksdale  1 , Macy G Wood  2 , Chad E Branecki  3 , Brooklin Zimmerman  4 , Elizabeth Lyden  5 , Thang T Nguyen  6 , Andrew Hatfield  7 , Scott Koepsell  8 , Jason Langenfeld  9 , Wesley G Zeger  10 , Michael C Wadman  11
Affiliations
Observational Study

Incidence of unknown COVID-19 infection in a cohort of emergency physicians and advance practice providers

Aaron Nathan Barksdale et al. Am J Emerg Med. 2023 Feb.

Abstract

Introduction: In United States, health care workers have been immersed in the COVID-19 pandemic since February 2020. Since availability of COVID-19 vaccines, there is limited literature investigating the incidence of unknown COVID-19 infections in physicians and Advanced Practitioner Providers (APPs) working in emergency departments (EDs). The primary objective is to determine the incidence unknown COVID-19 infection within a cohort of emergency physicians (EPs) and APPs.

Methods: Prospective observational study at a tertiary academic center with emergency medicine residency and 64,000 annual ED visits. EPs/APPs providing care to ED patients over the prior 12 months were eligible. Serum samples were collected between May 1 and June 30, 2022. Analysis utilized Luminex xMAP® SARS-CoV-2 Multi-Antigen IgG Assay for antibodies to Nucleocapsid, Receptor-binding domain, and Spike subunit 1. Mean Fluorescent Intensity (MFI) ≥ 700 was considered positive. Subjects completed 12 question survey assessing demographics and previously confirmed COVID-19 infection. Fisher's exact test evaluated associations of demographics and clinical characteristics with confirmed COVID-19 status. Analyses performed using SAS, Version 9.4. P < 0.05 considered statistically significant.

Results: Sixty-nine of 81 eligible subjects (85.2%) participated, 58.0% were male, 97.1% white, with mean age of 37. Eighteen subjects had MFI ≥ 700 strongly suggestive of prior infection, with 17.7% unknown. No statistically significant difference between age, gender, race, children in home, or household member with previously COVID-19 infection.

Conclusion: Unknown previous COVID-19 infection was less then expected in this cohort of EPs/APPs, and no association with individual characteristics, previously infected household member, or children in the home.

Keywords: Antibodies; COVID-19; Emergency medicine; Infection; SARS-CoV-2.

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Figures

Fig. 1
Fig. 1
Survey for emergency medicine providers undergoing SARS-CoV-2 serum antibody analysis.
Fig. 2
Fig. 2
SARS-CoV-2 antibody levels in 69 Emergency Medicine Providers (EMP). Serum collected from EMPs was analyzed using a multi-antigen assay to determine the Mean Fluorescent Intensity (MFI) of Nucleocapsid (N; blue bar) and Receptor-Binding Domain (RBD; orange bar) levels. Nucleocapsid antibodies are a unique marker for COVID-19 infection, while RBD antibodies can be from COVID-19 infection and post-vaccination for SARS-CoV-2. Nucleocapsid levels (MFI) superimposed on RBD MFI detected; the dotted line (700 MFI) represents the threshold for a positive antibody response (GraphPad Prism version 9.4.1). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)
See this image and copyright information in PMC

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