The protective effect of SARS-CoV-2 antibodies in Scottish healthcare workers

  1. Hani Abo-Leyah
  2. Stephanie Gallant
  3. Diane Cassidy
  4. Yan Hui Giam
  5. Justin Killick
  6. Beth Marshall
  7. Gordon Hay
  8. Caroline Snowdon
  9. Eleanor J. Hothersall
  10. Thomas Pembridge
  11. Rachel Strachan
  12. Natalie Gallant
  13. Benjamin J. Parcell
  14. Jacob George
  15. Elizabeth Furrie
  16. James D. Chalmers

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Abstract

Healthcare workers (HCWs) are believed to be at increased risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. It is not known to what extent the natural production of antibodies to SARS-CoV-2 is protective against re-infection.

Methods

A prospective observational study of HCWs in Scotland (UK) from May to September 2020 was performed. The Siemens SARS-CoV-2 total antibody assay was used to establish seroprevalence in this cohort. Controls, matched for age and sex to the general local population, were studied for comparison. New infections (up to 2 December 2020) post antibody testing were recorded to determine whether the presence of SARS-CoV-2 antibodies protects against re-infection.

Results

A total of 2063 health and social care workers were recruited for this study. At enrolment, 300 HCWs had a positive antibody test (14.5%). 11 out of 231 control sera tested positive (4.8%). HCWs therefore had an increased likelihood of a positive test (OR 3.4, 95% CI 1.85–6.16; p<0.0001). Dentists were most likely to test positive. 97.3% of patients who had previously tested positive for SARS-CoV-2 by reverse transcriptase (RT)-PCR had positive antibodies. 18.7% had an asymptomatic infection. There were 38 new infections with SARS-CoV-2 in HCWs who were previously antibody negative, and one symptomatic RT-PCR-positive re-infection. The presence of antibodies was therefore associated with an 85% reduced risk of re-infection with SARS-CoV-2 (hazard ratio 0.15, 95% CI 0.06–0.35; p=0.026).

Conclusion

HCWs were three times more likely to test positive for SARS-CoV-2 than the general population. Almost all infected individuals developed an antibody response, which was 85% effective in protecting against re-infection with SARS-CoV-2.

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  1. Version published to 10.1183/23120541.00080-2021
  2. Rapid Reviews Infectious Diseases

    Strength of evidence

    Reviewers: T Bruckner (UC Irvine) | 📒📒📒◻️◻️
    T Vilibić-Čavlek, Vladimir Savic (Croatian Institute) | 📗📗📗📗◻️ | P Galanis (National and Kapodistrian University) | 📒📒📒◻️◻️
    I Cockburn (Australian National University) | 📒📒📒◻️◻️ | T Roederer (Epicentre) | 📒📒📒◻️◻️

  3. Rapid Reviews Infectious Diseases

    Thomas Roederer

    Review 5: "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.

  4. Rapid Reviews Infectious Diseases

    Ian Cockburn

    Review 4: "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.

  5. Rapid Reviews Infectious Diseases

    Petros Galanis

    Review 3: "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.

  6. Rapid Reviews Infectious Diseases

    Tatjana Vilibić-Čavlek, Vladimir Savic

    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.

  7. Rapid Reviews Infectious Diseases

    Tim Bruckner

    Review 1: "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.

  8. ScreenIT

    SciScore for 10.1101/2020.10.02.20205641: (What is this?)

    Please note, not all rigor criteria are appropriate for all manuscripts.

    Table 1: Rigor

    Institutional Review Board StatementConsent: All participants gave written informed consent to participate.
    IRB: The study was approved by the West of Scotland Research Ethics committee, approval number 20/WS/0078 The inclusion criteria were: Employment as a health or social care worker and age over 16 years.
    Randomizationnot detected.
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    This is a one stop bridging chemiluminescent immunoassay (CLIA) method that detects antibodies against the receptor-binding domain (RBD) of the SARS-CoV-2 spike (S1) protein.
    S1
    suggested: None
    Software and Algorithms
    SentencesResources
    Statistical analysis: Data was analysed using IBM SPSS v25 and GraphPad Prism 8.1.2. Chi-squared and Fisher’s test were used as appropriate to compare proportions between groups.
    SPSS
    suggested: (SPSS, RRID:SCR_002865)
    GraphPad Prism
    suggested: (GraphPad Prism, RRID:SCR_002798)

    Results from OddPub: We did not detect open data. We also did not detect open code. Researchers are encouraged to share open data when possible (see Nature blog).

    Results from LimitationRecognizer: We detected the following sentences addressing limitations in the study:
    This study has potential limitations, including potentially that individuals more likely to believe they have had a SARS-CoV-2 like illness would be more likely to volunteer for such a study. Nevertheless, we were successful in enrolling participants who had never experienced a symptomatic infection and demonstrate an increased seroprevalence even amongst this group. We enrolled patients up to September 2020 and therefore potentially up to 4-5 months post-infection. This raises the possibility of antibodies waning over time21. This seems unlikely as a prior study found no evidence of waning of the Siemens assay over 4 months10, while a similar Total spike protein antibody assay showed no waning over time in a study from Iceland22. Other studies have reported increased infection rate in the BAME population23,24,25, we were unable to investigate this as NHS Tayside has a workforce which is 97% white. Important strengths of the study including the large sample sample size, representation of multiple staff groups and the extensive SARS-CoV-2 testing of symptomatic healthcare workers in the region allowing correlation between antibody testing and prior SARS-CoV-2 RT-PCR.6 In conclusion our study suggests that HCW are at increased risk of infection with SARS-COV-2 compared with the general population. Our study suggests a differential risk amongst hospital staff and a high proportion of undetected symptomatic and asymptomatic infections. This will help to inform targeted IPC strate...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We did not find any issues relating to the usage of bar graphs.

    Results from JetFighter: We did not find any issues relating to colormaps.

    Results from rtransparent:
    • Thank you for including a conflict of interest statement. Authors are encouraged to include this statement when submitting to a journal.
    • Thank you for including a funding statement. Authors are encouraged to include this statement when submitting to a journal.
    • No protocol registration statement was detected.

    About SciScore

    SciScore is an automated tool that is designed to assist expert reviewers by finding and presenting formulaic information scattered throughout a paper in a standard, easy to digest format. SciScore checks for the presence and correctness of RRIDs (research resource identifiers), and for rigor criteria such as sex and investigator blinding. For details on the theoretical underpinning of rigor criteria and the tools shown here, including references cited, please follow this link.

  9. Version published to 10.1101/2020.10.02.20205641v1 on medRxiv