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Review 2: "Seroprevalence of SARS-COV-2 Antibodies in Scottish Healthcare Workers"

This study reports a greater seroprevalence for antibodies among healthcare workers compared to the general population. Reviewers mentioned concerns over selection of the general population, response bias, and adjusting for potential cross-reactivity with other coronaviruses.

Published onDec 17, 2020
Review 2: "Seroprevalence of SARS-COV-2 Antibodies in Scottish Healthcare Workers"
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key-enterThis Pub is a Review of
Seroprevalence of SARS-COV-2 Antibodies in Scottish Healthcare Workers

Abstract Introduction Healthcare workers are believed to be at increased risk of SARS-CoV-2 infection. The extent of that increased risk compared to the general population and the groups most at risk have not been extensively studied.Methods A prospective observational study of health and social care workers in NHS Tayside (Scotland, UK) from May to September 2020. The Siemens SARS-CoV-2 total antibody assay was used to establish seroprevalence in this cohort. Patients provided clinical information including demographics and workplace information. Controls, matched for age and sex to the general Tayside population, were studied for comparison.Results A total of 2062 health and social care workers were recruited for this study. The participants were predominantly female (81.7%) and 95.2% were white. 299 healthcare workers had a positive antibody test (14.5%). 11 out of 231 control sera tested positive (4.8%). Healthcare workers therefore had an increased likelihood of a positive test (odds ratio 3.4 95% CI 1.85-6.16, p<0.0001). Dentists, healthcare assistants and porters were the job roles most likely to test positive. Those working in front-line roles with COVID-19 patients were more likely to test positive (17.4% vs. 13.4%, p=0.02). 97.1% of patients who had previously tested positive for SARS-CoV-2 by RT-PCR had positive antibodies, compared to 11.8% of individuals with a symptomatic illness who had tested negative. Anosmia was the symptom most associated with the presence of detectable antibodies.Conclusion In this study, healthcare workers were three times more likely to test positive for SARS-CoV-2 than the general population. The seroprevalence data in different populations identified in this study will be useful to protect healthcare staff during future waves of the pandemic.

RR:C19 Evidence Scale rating by reviewer:

  • Reliable. The main study claims are generally justified by its methods and data. The results and conclusions are likely to be similar to the hypothetical ideal study. There are some minor caveats or limitations, but they would/do not change the major claims of the study. The study provides sufficient strength of evidence on its own that its main claims should be considered actionable, with some room for future revision.



We have read with interest the manuscript entitled "Seroprevalence of SARS-CoV-2 Antibodies in Scottish Healthcare Workers" by Abo-Leyah, et al. In this prospective observational study, the authors analyzed the seroprevalence of SARS-CoV-2 infection in 2062 health and social care workers employed in the National Health Service in Tayside (Scotland, United Kingdom). A random selection of blood samples taken at General Practice Surgeries were tested as the MATCH study cohort. For detection of SARS-CoV-2 antibodies, a commercial chemiluminescent immunoassay (CLIA) method that detects antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike (S1) protein was used.

The results of the study showed that healthcare workers (HCW) were three times more likely to test SARS-CoV-2 positive than general population. The overall seroprevalence was 14.5% and varied significantly among HCW subgroups from 8.6% to 26% compared to 4.5% in the Scottish general population. Dentistry staff was identified as a subpopulation at the highest risk for COVID-19 (seroprevalence 26%), followed by health care assistants (seroprevalence 23.3%). The presented results also demonstrated that a significant proportion of SARS-CoV-2 seropositive HCW (18.5%) were asymptomatic.

There are some minor limitations of the study, but they do not change the major claims of the study. Although several limitations are discussed, one additional limitation needs to be addressed. Since only CLIA test was used for the antibody detection without confirmatory neutralization tests (neither surrogate ELISA neutralization test nor virus neutralization test in a cell culture), potential cross-reactivity with other coronaviruses should not be excluded with certainty.

Since the HCW are a population with an increased risk for SARS-CoV-2 infection, the seroprevalence data provides information on the extent of the disease (especially among asymptomatic cases who may potentially transmit the virus to their colleagues and patients) and contributes to a better understanding of the epidemiology of COVID-19 in this population group. In addition, the seroprevalence data identified in this large-scale seroepidemiological study will be useful to raise awareness and, thereby, protect HCW during the future waves of COVID-19 pandemic.

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