key: cord-1032707-sfv86gxc
authors: Shah, Vishal P.; Hainy, Caitlin M.; Swift, Melanie D.; Breeher, Laura E.; Theel, Elitza S.; Sampathkumar, Priya
title: Unrecognized severe acute respiratory coronavirus virus 2 (SARS-CoV-2) seroprevalence among healthcare personnel in a low-prevalence area
date: 2020-11-20
journal: Infection control and hospital epidemiology
DOI: 10.1017/ice.2020.1341
sha: cdef04108820c4e9ca4576d375f6687454a53412
doc_id: 1032707
cord_uid: sfv86gxc

nan

indeterminate samples were retested using either the Roche Diagnostics anti-SARS-CoV-2 Total Antibody Immunoassay (Roche Diag nostics, Rotkreuz, Switzerland) or the Ortho-Clinical Diagnostics anti-SARS-CoV-2 IgG Antibody Immunoassay (Ortho-Clinical Diagnostics, Raritan, NJ). Only participants with positive tests by 2 assays were considered seropositive for antibodies to SARS-CoV-2. RT-PCR testing records were assessed through occupational health records from March 9 through June 30, 2020. The χ 2 and Fisher exact tests were used for the statistical analysis.

In total, 586 participants were enrolled, and 568 completed the survey and laboratory analysis (Table 1) . Overall, 2 of 320 (0.63%) HCP in the high-risk cohort tested positive for IgG antibodies against SARS-CoV-2, while 0 of 248 (0%) tested positive in the low-risk cohort (OR, 3.90; P = .51). The 2 individuals with antibodies to SARS-CoV-2 did not report breaches in personal protective equipment (PPE), nor were they advised to quarantine due to a known exposure to a person with COVID-19. One seropositive study participant reported symptoms of chills, myalgias, diarrhea, and a headache, and the second participant reported a headache. A higher number of HCP in the high-risk cohort were placed on a quarantine due to known exposure to a person with COVID-19 compared to the low-risk cohort (odds ratio [OR], 12.1; P = .0016).

Based on role and employment location, there were 1,348 employees who would have been eligible to enroll in the high-risk cohort. From March 9 to June 30, 2020, 7 of these employees tested positive by RT-PCR, 3 of whom had known community exposures. The RT-PCR positive rate between the high-risk cohort (0.52%) and the non-high-risk cohort (0.57%) were similar and were also comparable to overall RT-PCR prevalence rates in the region (0.67% as of July 1, 2020). 6 Previous data describing COVID-19 infection rates in HCP have been mixed. The multistate study of frontline HCP and other studies have shown significant heterogeneity among frontline HCP that generally correlated with community rates. 4 A study evaluating IgG antibodies to SARS-CoV-2 among HCP in Germany found the overall rate of unrecognized prior infection to be 1.6%. 7 However, the use of single antibody assays in low-prevalence areas may lead to high rates of false-positive results. A Centers for Disease Control and Prevention (CDC) study assessing antibody Vishal P. Shah et al prevalence across 10 sites in the United States from March 23 to May 12, 2020, revealed highly variable prevalence rates ranging from 1% to 6.9%. 8 An orthogonal testing algorithm was utilized; however, the study did not specify whether individuals had been symptomatic or previously tested by RT-PCR.

Here, we present serology and RT-PCR data to determine the prevalence of recognized and unrecognized COVID-19 infections among HCP. In this low-prevalence setting, HCP in the high-risk cohort are much more likely to encounter persons with COVID-19 in the occupational setting compared to the community. Despite providing care to patients with COVID-19 and having higher odds of being quarantined due to an exposure to a person with COVID-19, the rate of SARS-CoV-2 infection based on combined seroconversion and RT-PCR positivity did not differ between high-and low-risk HCP, and they were similar to community rates.

Our study has several limitations. Given the kinetics of antibody development against SARS-CoV-2, individuals tested shortly after infection may not have mounted an antibody response. Additionally, the county in which the hospital is situated also had a low prevalence of COVID-19, as determined by the percentage of positive by RT-PCR tests.

Overall, HCP regularly caring for patients with COVID-19 did not have significantly higher rates of COVID-19 infection compared to other HCP at a tertiary-care center in Minnesota. In particular, rates of unrecognized infection were low. These data support the efficacy of current processes to identify and isolate COVID-19 patients and to limit HCP exposure to COVID-19 through administrative practices, training, and rigorous use of PPE.

Prevalence of SARS-CoV-2 infection among asymptomatic healthcare workers in the greater

Temporal dynamics in viral shedding and transmissibility of COVID-19

The laboratory diagnosis of coronavirus disease 2019-frequently asked questions

Seroprevalence of SARS-CoV-2 among frontline healthcare personnel in a multistate hospital network-13 academic medical centers

Performance characteristics of four high-throughput immunoassays for detection of IgG antibodies against SARS-CoV-2

COVID-19 Weekly Report

SARS-CoV-2-specific antibody detection in healthcare workers in Germany with direct contact to COVID-19 patients

Seroprevalence of antibodies to SARS-CoV-2 in 10 sites in the United States

Acknowledgments. We would like to thank our study coordinater, Katherine B. Erickson, for her contribution and support of this work.Financial support. No financial support was provided relevant to this article.

Diagnostics and Accelerate Diagnostics and receiving research funding from Ortho-Clinical Diagnostics. All other authors report no conflicts of interest relevant to this article.