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  • Prevalence, incidence and longevity of antibodies against SARS-CoV-2 among primary healthcare providers in Belgium: a prospective cohort study with 12 months of follow-up

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Infectious diseases
Original research
Prevalence, incidence and longevity of antibodies against SARS-CoV-2 among primary healthcare providers in Belgium: a prospective cohort study with 12 months of follow-up
  1. Niels Adriaenssens1,
  2. Beatrice Scholtes2,
  3. Robin Bruyndonckx3,4,5,
  4. Pauline Van Ngoc2,
  5. Jan Yvan Jos Verbakel6,7,
  6. An De Sutter8,
  7. Stefan Heytens8,
  8. Ann Van Den Bruel7,
  9. Isabelle Desombere9,
  10. Pierre Van Damme10,
  11. Herman Goossens5,
  12. Laetitia Buret2,
  13. Els Duysburgh11,
  14. Samuel Coenen1,5
  1. 1Family Medicine & Population Health, Centre for General Practice, University of Antwerp Faculty of Medicine and Health Sciences, Antwerp (Wilrijk), Belgium
  2. 2General Practice Department, Primary Care and Health Research Unit, Liege University, Liege, Belgium
  3. 3Interuniversity Institute for Biostatistics and statistical Bioinformatics (I-BIOSTAT), Hasselt University, Hasselt, Limburg, Belgium
  4. 4Epidemiology & Pharmacovigilance, P95, Leuven, Belgium
  5. 5Vaccine & Infectious Disease Institute, Laboratory of Medical Microbiology, University of Antwerp, Antwerp (Wilrijk), Belgium
  6. 6Nuffield Department of Primary Care Health Sciences, University of Oxford, Oxford, UK
  7. 7Department of Public Health and Primary Care, KU Leuven, Leuven, Flanders, Belgium
  8. 8Department of Public Health and Primary Care, Ghent University, Gent, Belgium
  9. 9Department of Infectious Diseases in Humans, Sciensano, Brussels, Belgium
  10. 10Vaccine & Infectious Disease Institute, Centre for the Evaluation of Vaccination, University of Antwerp Faculty of Medicine and Health Sciences, Antwerp (Wilrijk), Belgium
  11. 11Department of Epidemiology and Public Health, Sciensano, Brussels, Belgium
  1. Correspondence to Professor Samuel Coenen; samuel.coenen{at}uantwerpen.be

Abstract

Objectives To estimate the prevalence, incidence and longevity of antibodies against SARS-CoV-2 among primary healthcare providers (PHCPs).

Design Prospective cohort study with 12 months of follow-up.

Setting Primary care in Belgium.

Participants Any general practitioner (GP) working in primary care in Belgium and any other PHCP from the same GP practice who physically manages (examines, tests, treats) patients were eligible. A convenience sample of 3648 eligible PHCPs from 2001 GP practices registered for this study (3044 and 604 to start in December 2020 and January 2021, respectively). 3390 PHCPs (92,9%) participated in their first testing time point (2820 and 565, respectively) and 2557 PHCPs (70,1%) in the last testing time point (December 2021).

Interventions Participants were asked to perform a rapid serological test targeting IgM and IgG against the receptor binding domain of SARS-CoV-2 and to complete an online questionnaire at each of maximum eight testing time points.

Primary and secondary outcome measures The prevalence, incidence and longevity of antibodies against SARS-CoV-2 both after natural infection and after vaccination.

Results Among all participants, 67% were women and 77% GPs. Median age was 43 years. The seroprevalence in December 2020 (before vaccination availability) was 15.1% (95% CI 13.5% to 16.6%), increased to 84.2% (95% CI 82.9% to 85.5%) in March 2021 (after vaccination availability) and reached 93.9% (95% CI 92.9% to 94.9%) in December 2021 (during booster vaccination availability and fourth (delta variant dominant) COVID-19 wave). Among not (yet) vaccinated participants the first monthly incidence of antibodies against SARS-CoV-2 was estimated to be 2.91% (95% CI 1.80% to 4.01%). The longevity of antibodies is higher in PHCPs with self-reported COVID-19 infection.

Conclusions This study confirms that occupational health measures provided sufficient protection when managing patients. High uptake of vaccination resulted in high seroprevalence of SARS-CoV-2 antibodies in PHCPs in Belgium. Longevity of antibodies was supported by booster vaccination and virus circulation.

Trial registration number NCT04779424.

  • PRIMARY CARE
  • COVID-19
  • GENERAL MEDICINE (see Internal Medicine)
  • Epidemiology

Data availability statement

Data are available on reasonable request. The relevant anonymised patient-level data as well as statistical code that support the findings of this study are available from the corresponding author on reasonable request.

http://creativecommons.org/licenses/by-nc/4.0/

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/.

http://dx.doi.org/10.1136/bmjopen-2022-065897

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    Data availability statement

    Data are available on reasonable request. The relevant anonymised patient-level data as well as statistical code that support the findings of this study are available from the corresponding author on reasonable request.

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    Footnotes

    • NA and BS are joint first authors.

    • Twitter @jan_verbakel

    • ED and SC contributed equally.

    • Contributors The study concept and design was initiated by SC, NA, BS and ED and finalised with contributions from JYJV, ADS, SH, AVDB, ID, PVD, HG. SC, NA, BS and PVN conducted registration and data collection. Analysis was performed by RB. NA prepared the first draft of the manuscript. All authors (NA, BS, RB, PVN, JYJV, ADS, SH, AVDB, ID, PVD, HG, LB, ED and SC) provided edits and critiqued the manuscript for intellectual content, approved the submitted version, were involved in the interpretation of data, and agree to be accountable for all aspects of the work. NA and BS contributed equally to this work as first author. ED and SC contributed equally to this work as last author. SC is acting as guarantor.

    • Funding 'This work was supported by Sciensano, grant number (OZ8478)' JYJV was further supported by the National Institute for Health and Care Research (NIHR) Community Healthcare MedTech and In Vitro Diagnostics Co-operative at Oxford Health NHS Foundation Trust.

    • Disclaimer The views expressed are those of the author(s) and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

    • Competing interests None declared.

    • Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.