SARS-CoV-2 antibody dynamics over time and risk factors associated with infection and long COVID-19 symptoms in large working environments

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Factors influencing SARS-CoV-2 antibody dynamics, transmission, waning and long COVID-19 symptomatology are still not fully understood.

In the Danish section of the Novo Nordisk Group, we performed a prospective seroepidemiological study during the first and second waves of the COVID-19 pandemic. All employees and their household members (>18 years) were invited to participate in a baseline (June–August 2020), 6-month follow-up (December 2020–January 2021), and 12-month follow-up (August 2021) sampling. In total, 18,614 accepted and provided at least one blood sample and completed a questionnaire regarding socioeconomic background, health status, previous SARS-CoV-2 infection, and persistent symptoms. Total antibody and specific IgM, IgG and IgA levels against recombinant receptor binding domain were tested.

At baseline, the SARS-CoV-2-antibody seroprevalence was 3.9%. At 6-month follow-up, the seroprevalence was 9.1%, while at 12-month follow-up, the seroprevalence was 94.4% (after the vaccine roll-out). Male sex and younger age (18–40 years) were significant risk factors for seropositivity. From baseline to the 6-month sampling, we observed a substantial waning of IgM, IgG and IgA levels (p < 0.001), regardless of age, sex and initial antibody level. An increased antibody level was found in individuals infected prior to vaccination compared to vaccinated infection naïves (p < 0.0001). Approximately a third of the seropositive individuals reported one or more persistent COVID-19 symptoms, with anosmia and/or ageusia (17.5%) and fatigue (15.3%) being the most prevalent.

The study provides a comprehensive insight into SARS-CoV-2 antibody seroprevalence following infection and vaccination, waning, persistent COVID-19 symptomatology and risk factors for seropositivity in large working environments.
TidsskriftJournal of Internal Medicine
Udgave nummer6
Sider (fra-til)763-781
Antal sider19
StatusUdgivet - 2023

Bibliografisk note

Funding Information:
First of all, we want to thank all the Novo Nordisk Group employees and their respective household members that made this study possible. The authors wish to thank Sif Kaas Nielsen, Mads Engelhardt Knudsen, and Bettina Eide Holm from the Laboratory of Molecular Medicine at Rigshospitalet; Helle Bach Petersen, Berit Engberg, and Juliano Olsen from Novo Nordisk A/S for their excellent technical and logistic assistance. The authors also thank Else Marie Agger from Novo Nordisk A/S for her invaluable help. Novo Nordisk A/S is acknowledged for their help in producing recombinant proteins. This work was financially supported by grants from the Carlsberg Foundation (CF20‐0045) and the Novo Nordisk Foundation (NFF205A0063505 and NNF20SA0064201).

Publisher Copyright:
© 2023 The Authors. Journal of Internal Medicine published by John Wiley & Sons Ltd on behalf of Association for Publication of The Journal of Internal Medicine.

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