SARS-CoV-2 seroprevalence survey among 18,000 healthcare and administrative personnel at hospitals, pre-hospital services, and specialist practitioners in the Central Denmark Region

Abstract

Objectives: The objective of this study was to perform a large seroprevalence survey on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among Danish healthcare workers to identify high risk groups. Design: Cross-sectional survey. Setting: All healthcare workers and administrative personnel at the seven hospitals, pre-hospital services and specialist practitioner clinics in the Central Denmark Region were invited by e-mail to be tested for antibodies against SARS-CoV-2 by a commercial SARS-CoV-2 total antibody enzyme-linked immunosorbent assay (ELISA, Wantai Biological Pharmacy Enterprise Co., Ltd., Beijing, China). Participants: A total of 25,950 participants were invited. Of these, 17,987 (69%) showed up for blood sampling, and 17,971 had samples available for SARS-CoV-2 antibody testing. Main outcome measures: 1) Prevalence of SARS-CoV-2 antibodies; 2) Risk factors for seropositivity; 3) Association of SARS-CoV-2 RNA and antibodies. Results: After adjustment for assay sensitivity and specificity, the overall seroprevalence was 3.4% (CI: 2.5%-3.8%). The seroprevalence was higher in the western part of the region than in the eastern part (11.9% vs 1.2%, difference: 10.7 percentage points, CI: 9.5-12.2). In the high prevalence area, the emergency departments had the highest seroprevalence (29.7%) while departments without patients or with limited patient contact had the lowest seroprevalence (2.2%). Multivariable logistic regression analysis with age, sex, and profession as the predictors showed that nursing staff, medical doctors, and biomedical laboratory scientists had a higher risk than medical secretaries, who served as reference (OR = 7.3, CI: 3.5-14.9; OR = 4., CI: 1.8-8.9; and OR = 5.0, CI: 2.1-11.6, respectively). Among the total 668 seropositive participants, 433 (64.8%) had previously been tested for SARS-CoV-2 RNA, and 50.0% had a positive RT-PCR result. A total of 98% of individuals who had a previous positive viral RNA test were also found to be seropositive. Conclusions: We found large differences in the prevalence of SARS-CoV-2 antibodies in staff working in the healthcare sector within a small geographical area of Denmark and signs of in-hospital transmission. Half of all seropositive staff had been tested positive by PCR prior to this survey. This study raises awareness of precautions which should be taken to avoid in-hospital transmission. Additionally, regular testing of healthcare workers for SARS-CoV-2 should be considered to identify areas with increased transmission. Trial registration: The study is approved by the Danish Data Protection Agency (1-16-02-207-20).

Severe acute respiratory syndrome coronavirus 2 seroprevalence survey among 10,256 workers in Kuwait

“…With regard to gender, the seroprevalence was significantly higher in males (6.2%) than females (1.9%) (p<0.001). This data seems be in line with several reports [9] , [16] . However, other studies reported that the seroprevalence among males and females was similar [11] , [17] .…”

“…Higher seroprevalences was also reported in New York (12.5%) [13] . Whereas, a low seroprevalence was reported Southern Brazil (0.05%-0.22%) [14] , Greece (0.36%) [15] , Denmark (2%) [16] , France (2.7%) [17] , and Wuhan (3.2%-3.8%) [18] in the beginning of COVID-19 pandemic. The seroprevalence can vary according to different sites and the selected group and can increase with time in the longitudinal follow-up [9] .…”

Serologic SARS-CoV-2 testing in healthcare workers with positive RT-PCR test or Covid-19 related symptoms

“…The regression analysis, based on LFIA, offers the most informative figures with respect to determinants of positive anti-SARS-CoV-2 antibodies; the fact that they are consistent with the results of the comparable analysis ELISA, provides additional support. To our knowledge, these are the first results reported in the scientific literature on determinants of serologic response among HCWs infected by SARS-CoV-2, and are in line with similar analysis conducted among HCWs regardless of infection status [8,10-12].…”

“…Another study found among 126 RT-PCR positive HCWs from Belgium, a proportion of positive CLIA test of 86.5% [9]. Finally, in a study of 340 RT-PCR positive HCWs from Denmark, a total of 334 subjects were tested positive for total ELISA Ig [10]. Our results, based on either LFIA or ECLIA, testing the largest group of RT-PCR HCWs studied so far, are comparable to those of previous studies.…”

“…Another study found among 126 RT-PCR positive HCWs from Belgium, a proportion of positive CLIA test of 86.5%[9]. Finally, in a study of 340 RT-PCR positive HCWs from Denmark, a total of 334 subjects were tested positive for total ELISA Ig[10]. Our results, based on either LFIA or ECLIA, testing the largest group of RT-PCR HCWs studied so far, are comparable to those of previous studies.The regression analysis, based on LFIA, offers the most informative figures with respect to determinants of positive anti-SARS-CoV-2 antibodies; the fact that they are consistent with the results of the comparable analysis ELISA, provides additional support.…”