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      SARS-CoV-2 seroprevalence and asymptomatic viral carriage in healthcare workers: a cross-sectional study

      1 , 2 , 1 , 3 , 3 , 4 , 5 , 1 , 1 , 2 , 1 , 1 , 1 , 2 , 4 , 2 , 6 , 2 , 7 , 7 , 2 , 4 , 8 , 8 , 1 , 4 , 8 , 5 , 9 , 8 , 4 , 5 , 3 , 10 , 8 , 3 , 1 , 10 , , 1 , 2


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      viral infection, infection control, clinical epidemiology, respiratory infection

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          To determine the rates of asymptomatic viral carriage and seroprevalence of SARS-CoV-2 antibodies in healthcare workers.


          A cross-sectional study of asymptomatic healthcare workers undertaken on 24/25 April 2020.


          University Hospitals Birmingham NHS Foundation Trust (UHBFT), UK.


          545 asymptomatic healthcare workers were recruited while at work. Participants were invited to participate via the UHBFT social media. Exclusion criteria included current symptoms consistent with COVID-19. No potential participants were excluded.


          Participants volunteered a nasopharyngeal swab and a venous blood sample that were tested for SARS-CoV-2 RNA and anti-SARS-CoV-2 spike glycoprotein antibodies, respectively. Results were interpreted in the context of prior illnesses and the hospital departments in which participants worked.

          Main outcome measure

          Proportion of participants demonstrating infection and positive SARS-CoV-2 serology.


          The point prevalence of SARS-CoV-2 viral carriage was 2.4% (n=13/545). The overall seroprevalence of SARS-CoV-2 antibodies was 24.4% (n=126/516). Participants who reported prior symptomatic illness had higher seroprevalence (37.5% vs 17.1%, χ 2=21.1034, p<0.0001) and quantitatively greater antibody responses than those who had remained asymptomatic. Seroprevalence was greatest among those working in housekeeping (34.5%), acute medicine (33.3%) and general internal medicine (30.3%), with lower rates observed in participants working in intensive care (14.8%). BAME (Black, Asian and minority ethnic) ethnicity was associated with a significantly increased risk of seropositivity (OR: 1.92, 95% CI 1.14 to 3.23, p=0.01). Working on the intensive care unit was associated with a significantly lower risk of seropositivity compared with working in other areas of the hospital (OR: 0.28, 95% CI 0.09 to 0.78, p=0.02).

          Conclusions and relevance

          We identify differences in the occupational risk of exposure to SARS-CoV-2 between hospital departments and confirm asymptomatic seroconversion occurs in healthcare workers. Further investigation of these observations is required to inform future infection control and occupational health practices.

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          Most cited references 14

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          Cryo-EM structure of the 2019-nCoV spike in the prefusion conformation

          Structure of the nCoV trimeric spike The World Health Organization has declared the outbreak of a novel coronavirus (2019-nCoV) to be a public health emergency of international concern. The virus binds to host cells through its trimeric spike glycoprotein, making this protein a key target for potential therapies and diagnostics. Wrapp et al. determined a 3.5-angstrom-resolution structure of the 2019-nCoV trimeric spike protein by cryo–electron microscopy. Using biophysical assays, the authors show that this protein binds at least 10 times more tightly than the corresponding spike protein of severe acute respiratory syndrome (SARS)–CoV to their common host cell receptor. They also tested three antibodies known to bind to the SARS-CoV spike protein but did not detect binding to the 2019-nCoV spike protein. These studies provide valuable information to guide the development of medical counter-measures for 2019-nCoV. Science, this issue p. 1260
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            Detection of SARS-CoV-2 in Different Types of Clinical Specimens

            This study describes results of PCR and viral RNA testing for SARS-CoV-2 in bronchoalveolar fluid, sputum, feces, blood, and urine specimens from patients with COVID-19 infection in China to identify possible means of non-respiratory transmission.
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              OpenSAFELY: factors associated with COVID-19 death in 17 million patients

              COVID-19 has rapidly impacted on mortality worldwide. 1 There is unprecedented urgency to understand who is most at risk of severe outcomes, requiring new approaches for timely analysis of large datasets. Working on behalf of NHS England we created OpenSAFELY: a secure health analytics platform covering 40% of all patients in England, holding patient data within the existing data centre of a major primary care electronic health records vendor. Primary care records of 17,278,392 adults were pseudonymously linked to 10,926 COVID-19 related deaths. COVID-19 related death was associated with: being male (hazard ratio 1.59, 95%CI 1.53-1.65); older age and deprivation (both with a strong gradient); diabetes; severe asthma; and various other medical conditions. Compared to people with white ethnicity, black and South Asian people were at higher risk even after adjustment for other factors (HR 1.48, 1.29-1.69 and 1.45, 1.32-1.58 respectively). We have quantified a range of clinical risk factors for COVID-19 related death in the largest cohort study conducted by any country to date. OpenSAFELY is rapidly adding further patients’ records; we will update and extend results regularly.

                Author and article information

                BMJ Publishing Group (BMA House, Tavistock Square, London, WC1H 9JR )
                August 2020
                28 August 2020
                [1 ] departmentClinical Immunology Service , University of Birmingham College of Medical and Dental Sciences , Birmingham, UK
                [2 ] University Hospitals Birmingham NHS Foundation Trust , Birmingham, UK
                [3 ] departmentInstitute of Immunology and Immunotherapy , University of Birmingham , Birmingham, UK
                [4 ] departmentInstitute of Microbiology and Infection , University of Birmingham , Birmingham, UK
                [5 ] departmentSchool of Biological Sciences , University of Southampton , Southampton, UK
                [6 ] Public Health England Midlands and East Region , Birmingham, UK
                [7 ] departmentInstitute of Inflammation and Ageing , University of Birmingham , Birmingham, UK
                [8 ] departmentSurgical Research Laboratory, Institute of Cancer and Genomic Sciences , University of Birmingham , Birmingham, UK
                [9 ] departmentOxford Glycobiology Institute, Department of Biochemistry , University of Oxford , Oxford, UK
                [10 ] departmentUniversity Hospitals Birmingham NHS Foundation Trust and University of Birmingham , NIHR Biomedical Research Centre , Birmingham, UK
                Author notes
                [Correspondence to ] Professor Alex G Richter, Clinical Immunology Service, University of Birmingham College of Medical and Dental Sciences, Birmingham B15 2TT, UK; a.g.richter@ 123456bham.ac.uk
                © Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.

                This is an open access article distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited, appropriate credit is given, any changes made indicated, and the use is non-commercial. See:  http://creativecommons.org/licenses/by-nc/4.0/.

                Funded by: CRUK Centre Birmingham;
                Award ID: C17422/A25154
                Funded by: Scripps Consortium for HIV Vaccine Development;
                Award ID: AI144462
                Funded by: FundRef http://dx.doi.org/10.13039/100000865, Bill and Melinda Gates Foundation;
                Award ID: OPP1084519 and OPP1115782
                Funded by: Birmingham Experimental Cancer Medicine Centre;
                Award ID: C11497/A25127
                Respiratory Infection
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