SARS-CoV-2 Seroprevalence and Antibody Kinetics Among Health Care Workers in a Spanish Hospital After 3 Months of Follow-up

  1. Gemma Moncunill
  2. Alfredo Mayor
  3. Rebeca Santano
  4. Alfons Jiménez
  5. Marta Vidal
  6. Marta Tortajada
  7. Sergi Sanz
  8. Susana Méndez
  9. Anna Llupià
  10. Ruth Aguilar
  11. Selena Alonso
  12. Diana Barrios
  13. Carlo Carolis
  14. Pau Cisteró
  15. Eugenia Chóliz
  16. Angeline Cruz
  17. Silvia Fochs
  18. Chenjerai Jairoce
  19. Jochen Hecht
  20. Montserrat Lamoglia
  21. Mikel J Martínez
  22. Javier Moreno
  23. Robert A Mitchell
  24. Natalia Ortega
  25. Nuria Pey
  26. Laura Puyol
  27. Marta Ribes
  28. Neus Rosell
  29. Antía Figueroa-Romero
  30. Patricia Sotomayor
  31. Sara Torres
  32. Sarah Williams
  33. Sonia Barroso
  34. Anna Vilella
  35. Antoni Trilla
  36. Pilar Varela
  37. Carlota Dobaño
  38. Alberto L Garcia-Basteiro

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Abstract

Background

At the COVID-19 spring 2020 pandemic peak in Spain, prevalence of SARS-CoV-2 infection in a cohort of 578 randomly selected health care workers (HCWs) from Hospital Clínic de Barcelona was 11.2%.

Methods

A follow-up survey 1 month later (April-May 2020) measured infection by rRT-PCR and IgM, IgA, and IgG to the receptor-binding domain of the spike protein by Luminex. Antibody kinetics, including IgG subclasses, was assessed until month 3.

Results

At month 1, the prevalence of infection measured by rRT-PCR and serology was 14.9% (84/565) and seroprevalence 14.5% (82/565). We found 25 (5%) new infections in 501 participants without previous evidence of infection. IgM, IgG, and IgA levels declined in 3 months (antibody decay rates 0.15 [95% CI, .11–.19], 0.66 [95% CI, .54–.82], and 0.12 [95% CI, .09–.16], respectively), and 68.33% of HCWs had seroreverted for IgM, 3.08% for IgG, and 24.29% for IgA. The most frequent subclass responses were IgG1 (highest levels) and IgG2, followed by IgG3, and only IgA1 but no IgA2 was detected.

Conclusions

Continuous and improved surveillance of SARS-CoV-2 infections in HCWs remains critical, particularly in high-risk groups. The observed fast decay of IgA and IgM levels has implications for seroprevalence studies using these isotypes.

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  1. ScreenIT

    SciScore for 10.1101/2020.08.23.20180125: (What is this?)

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

    Table 1: Rigor

    Institutional Review Board StatementConsent: Written informed consent was obtained from all study participants prior to study initiation.
    IRB: The study was approved by the Ethics Committee at HCB (Ref number: HCB/2020/0336).
    RandomizationStudy Design and Population: We performed the second cross-sectional survey (April 27th to May 6th, 2020) of a 4-stage seroprevalence study in a cohort of 578 HCW who had been randomly selected and recruited from a total of 5598 HCW registered at Hospital Clínic de
    Blindingnot detected.
    Power Analysisnot detected.
    Sex as a biological variablenot detected.

    Table 2: Resources

    Antibodies
    SentencesResources
    IgM, IgG and IgA antibodies to receptor-binding domain (RBD) of the spike glycoprotein of SARS-CoV-2, kindly donated by the Krammer lab (Mount Sinai, New York) [13], were measured as in the baseline survey of this cohort [3].
    IgM , IgG
    suggested: None
    IgA
    suggested: None
    Software and Algorithms
    SentencesResources
    Analyses were undertaken using Stata/SE software version 16.1 and R studio version R-3.5.1 [15] (packages tidyverse and pheatmap).
    Stata/SE
    suggested: None

    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:
    The main limitation of this study is the small sample size for the analysis of factors associated with SARS-CoV-2 infection. In addition, there may be a recall bias in some reported data such as symptoms. In addition, antibody responses were only analyzed using one antigen and other viral proteins may elicit different responses in different populations [14], thus we could have slightly underestimated the overall seroprevalence of infection. Finally, kinetics of antibody responses and antibody decay rates have to be interpreted with caution as only two timepoints have been analyzed and rates may change depending on the baseline levels, and if levels are measured at the peak response or at the later steady-state period. Data from next timepoints will complete kinetics information. Our findings reinforce the importance of strengthening SARS-CoV-2 surveillance among HCW. Despite having implemented regular rRT-PCR screenings, SARS-CoV-2 infections may go undetected. The lower antibody levels in the asymptomatic and mild cases, and the decay of IgA and IgM, have implications for seroprevalence studies as these isotypes may be undetectable 1-2 months post-infection. Although we could not show any evidence on IgG antibody decay after around 2 months from initial infection, we hope that subsequent surveys might provide some insight on this decay. Longer follow-up visits of this cohort will allow assessing the duration of IgG and IgG subclass responses and their role in protection from...

    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.
    • Thank you for including a protocol registration statement.

    About SciScore

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  2. Version published to 10.1093/infdis/jiaa696
  3. Version published to 10.1101/2020.08.23.20180125v1 on medRxiv