Severe Acute Respiratory Syndrome Coronavirus 2 Seroprevalence Survey Among 17 971 Healthcare and Administrative Personnel at Hospitals, Prehospital Services, and Specialist Practitioners in the Central Denmark Region

Abstract

Background The objective of this study was to perform a seroprevalence survey on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among Danish healthcare workers to identify high risk groups. Methods All healthcare workers and administrative personnel at the seven hospitals, pre-hospital services and specialist practitioner clinics in the Central Denmark Region were invited to be tested by a commercial SARS-CoV-2 total antibody enzyme-linked immunosorbent assay (ELISA, Wantai Biological Pharmacy Enterprise Co., Ltd., Beijing, China). Results A total of 25,950 participants were invited. Of these, 17,971 had samples available for SARS-CoV-2 antibody testing. 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%). 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. 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. 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. Regular testing of healthcare workers for SARS-CoV-2 should be considered to identify areas with increased transmission.

SARS-CoV-2 Seroprevalence Survey in People Involved in Different Essential Activities during the General Lock-Down Phase in the Province of Prato (Tuscany, Italy)

“…No age or sex differences were found in the seroprevalence of antibodies against SARS-CoV-2. These results are in line with what emerged in previous researches [17,[24][25][26][27][28].…”

“…Only a few studies have reported a comparison between the seroprevalence of healthcare workers and the background population of the area [17,18]. Similar to our findings, results of these studies showed the presence of high seroprevalence among healthcare workers and low seroprevalence in the background population of the hospitals' community area, thus suggesting in-hospital transmission.…”

“…Results showed that the seroprevalence of the "health service" group was 4.1%; this percentage is in line with the ones found in health care workers of other Italian regions [16] and European Countries [17,18,29]. However, results from other studies reported a large range in the levels of seroprevalence in health care workers, with some studies reporting seroprevalence differences even within small geographical areas [15,17,30,31]. These differences in the seroprevalence in healthcare workers may reflect the specific COVID-19 epidemic situations of the geographical areas in which the studies were performed; furthermore, they may be the result of different access to personal protective equipment and proper training.…”

“…In the Italian scenario, the Ministry of Health supported by the Scientific Committee has recognized the importance of carrying out serosurveys in order to assess the spreading of SARS-CoV-2 [14]. The first results from SARS-CoV-2 serosurveys in health care workers have begun to appear in the literature [15][16][17], but very limited research has examined other categories of essential workers or compared the risk of infection with that of the general population [18].…”

The Many Faces of Covid-19 at a Glance: A University Hospital Multidisciplinary Account From Milan, Italy

“…In line with our infection rate, a later large Italian study by Porru et al ( 37 ) identified positive nasopharyngeal swabs in 4% of Italian health workers. Another study on healthcare workers found in 17,971 samples for SARS-CoV-2 antibody testing an overall seroprevalence of 3.4% (confidence interval: 2.5–3.8%) ( 38 ). Emergency departments had the highest seroprevalence (29.7%), whereas departments without patients or with limited patient contact had the lowest (2.2%).…”