To the Editor:
Health care workers who frequently care for infected patients may be at higher risk of coronavirus disease 2019 (COVID-19) compared with the general population.1 The emergency department (ED) represents a high-risk environment because the COVID-19 status of ED patients is frequently unknown, and ED providers must test for the disease and perform aerosol-generating procedures. A prior study of ED providers found severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in 23 of 50 ED providers (46%) in New York City. We conducted this study to estimate the seroprevalence of SARS-CoV-2 antibodies in ED providers at an academic ED and review the clinical history of providers with evidence of prior infection.
We conducted a prospective, cross-sectional study to estimate the seroprevalence of antibodies to SARS-CoV-2 among ED providers (attending physicians, nurses, midlevel practitioners, patient care technicians, and pharmacists) at an academic medical center from September 1 to October 15, 2020. Exclusion criteria were pregnancy or immunocompromise. Participants underwent venipuncture to measure SARS-CoV-2 immunoglobulin G (IgG) antibodies. Samples were tested with a chemiluminescent immunoassay for IgG antibodies to the nucleocapsid antigen (Abbott Architect SARS-CoV-2 IgG; Abbot Laboratories, Abbott Park, IL). Positive results were confirmed by testing with a different chemiluminescent immunoassay for IgG antibodies to the S1/S2 spike antigens (Diasorin Liaison SARS-CoV-2 S1/S2 IgG; Diasorin Inc., Cypress, CA). Both assays have excellent test characteristics.
Of 360 ED patient care staff, 139 study participants were included: 90 women (64.7%) and 88 whites (63.3%), with a median age of 36 years (interquartile range 27 to 61). A total of 126 of 139 participants (90.6%) reported contact with COVID-19–positive patients, 10 of these (7.9%) without personal protective equipment. A total of 5 participants (3.6%) judged that they had a 76% to 100% likelihood for having antibodies. Four of the providers had antibodies to SARS-CoV-2, resulting in a seroprevalence of 4 of 139 (2.9%; exact 95% confidence interval 0.8% to 7.2%) (Table ). Three of the 4 seropositive participants were emergency physicians who had a prior diagnosis of COVID-19 based on a prior positive polymerase chain reaction test result and judged that they had a 76% to 100% likelihood of seropositivity. One seropositive participant, an ED nurse, had not received a prior diagnosis of COVID-19. This individual traveled at the beginning of February and subsequently developed fever and cough for 14 days, before the widespread availability of polymerase chain reaction testing.
Table.
Characteristics of the study participants.
| Characteristic | Number | Percentage |
|---|---|---|
| Total N | 139 | |
| Sex | ||
| Women | 90 | 64.7 |
| Race | ||
| Asian | 31 | 22.3 |
| Black | 4 | 2.9 |
| White | 88 | 63.3 |
| Other/multiple | 16 | 11.5 |
| Ethnicity | ||
| Latinx | 15 | 10.8 |
| Age | ||
| Mean (SD) | 38.2 | 9.5 |
| Median (IQR) | 36 | 27–61 |
| Site | ||
| Adult hospital ED | 112 | 80.6 |
| Children’s hospital ED | 27 | 19.4 |
| Provider type | ||
| ED nurse | 64 | 46.0 |
| Attending physician | 31 | 22.3 |
| Resident physician | 23 | 16.5 |
| Advanced practice provider | 7 | 5.0 |
| Patient care technician | 9 | 6.5 |
| Other | 5 | 3.6 |
| Prior diagnosis of COVID-19 based on PCR testing | ||
| Yes | 4 | 2.9 |
| SARS-CoV-2 IgG test result | ||
| Positive | 4 | 2.9 |
IQR, Interquartile range; PCR, polymerase chain reaction.
A pediatric ED nurse reported traveling in February and subsequently experiencing symptoms of malaise, headache, loss of smell, and shortness of breath, leading to a positive polymerase chain reaction and positive antibody test result in May 2020; the nurse had a negative result in our study. Treating this individual as having had COVID-19 raises the prevalence of prior infection in our sample to 5 of 139=3.6% (exact 95% confidence interval 1.2% to 8.2%).
It is likely that seroprevalence among frontline providers varies with the cumulative incidence of COVID-19 in the communities they serve. The prevalence of prior infection in our sample is lower than the seroprevalence in some studies of frontline and ED providers, such as Vanderbilt,2 Montefiore, and Coney Island Hospital,3 reporting respective seroprevalences of 8.2%, 31.2%, and 46%. San Francisco has had a low seroprevalence of antibodies, with an age- and sex-adjusted seroprevalence of 1.0%.4 We found a low SARS-CoV-2 seroprevalence among our ED providers, similar to other low community-seroprevalence EDs.
Footnotes
Fundingandsupport: By Annals policy, all authors are required to disclose any and all commercial, financial, and other relationships in any way related to the subject of this article as per ICMJE conflict of interest guidelines (see www.icmje.org). The authors have stated that no such relationships exist. Funded by a University of California Office of the President COVID-19 Research Seed Funding Grant.
References
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