Impact of baseline SARS-CoV-2 antibody status on syndromic surveillance and the risk of subsequent COVID-19—a prospective multicenter cohort study

  1. Philipp Kohler
  2. Sabine Güsewell
  3. Marco Seneghini
  4. Thomas Egger
  5. Onicio Leal
  6. Angela Brucher
  7. Eva Lemmenmeier
  8. J. Carsten Möller
  9. Philip Rieder
  10. Markus Ruetti
  11. Reto Stocker
  12. Danielle Vuichard-Gysin
  13. Benedikt Wiggli
  14. Ulrike Besold
  15. Stefan P. Kuster
  16. Allison McGeer
  17. Lorenz Risch
  18. Andrée Friedl
  19. Matthias Schlegel
  20. Pietro Vernazza
  21. Christian R. Kahlert

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Abstract

Background

In a prospective healthcare worker (HCW) cohort, we assessed the risk of SARS-CoV-2 infection according to baseline serostatus.

Methods

Baseline serologies were performed among HCW from 23 Swiss healthcare institutions between June and September 2020, before the second COVID-19 wave. Participants answered weekly electronic questionnaires covering information about nasopharyngeal swabs (PCR/rapid antigen tests) and symptoms compatible with coronavirus disease 2019 (COVID-19). Screening of symptomatic staff by nasopharyngeal swabs was routinely performed in participating facilities. We compared numbers of positive nasopharyngeal tests and occurrence of COVID-19 symptoms between HCW with and without anti-nucleocapsid antibodies.

Results

A total of 4812 HCW participated, wherein 144 (3%) were seropositive at baseline. We analyzed 107,807 questionnaires with a median follow-up of 7.9 months. Median number of answered questionnaires was similar (24 vs. 23 per person, P = 0.83) between those with and without positive baseline serology. Among 2712 HCW with ≥ 1 SARS-CoV-2 test during follow-up, 3/67 (4.5%) seropositive individuals reported a positive result (one of whom asymptomatic), compared to 547/2645 (20.7%) seronegative participants, 12 of whom asymptomatic (risk ratio [RR] 0.22; 95% confidence interval [CI] 0.07 to 0.66). Seropositive HCWs less frequently reported impaired olfaction/taste (6/144, 4.2% vs. 588/4674, 12.6%, RR 0.33, 95% CI 0.15–0.73), chills (19/144, 13.2% vs. 1040/4674, 22.3%, RR 0.59, 95% CI 0.39–0.90), and limb/muscle pain (28/144, 19.4% vs. 1335/4674, 28.6%, RR 0.68 95% CI 0.49–0.95). Impaired olfaction/taste and limb/muscle pain also discriminated best between positive and negative SARS-CoV-2 results.

Conclusions

Having SARS-CoV-2 anti-nucleocapsid antibodies provides almost 80% protection against SARS-CoV-2 re-infection for a period of at least 8 months.

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  1. Version published to 10.1186/s12916-021-02144-9
  2. ScreenIT

    SciScore for 10.1101/2021.06.09.21258422: (What is this?)

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

    Table 1: Rigor

    EthicsIRB: Study approval was granted by the ethics committee of Eastern Switzerland (#2020-00502).
    Sex as a biological variablenot detected.
    RandomizationTo verify the completeness and accuracy of self-reported nasopharyngeal results, all self-reported positive tests and a random sample of negative test results were cross-checked with the database of the division of occupational health for a subgroup of HCWs from the largest participating institution.
    Blindingnot detected.
    Power Analysisnot detected.

    Table 2: Resources

    No key resources detected.

    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 approach has the inherent limitation that people who are seropositive might be less likely to undergo testing, as seen in our data. In addition to testing for SARS-CoV-2, we therefore used a second approach to assess the protective effect of seropositivity on subsequent COVID-19. Using weekly symptom frequency as proxy for COVID-19 allows comparing incidence of COVID-19 irrespective of whether patients underwent testing or not. Of course, this signal is being diluted by infections caused by other respiratory viruses, especially for symptoms like coryza, sore throat, cough or fever. However, certain symptoms such as loss of taste or smell and myalgias have already been shown by others to be more specific for COVID-19 [15,16]. The fact that exactly these symptoms occurred less frequently among those with antibodies at baseline supports our finding of a reduced risk for SARS-CoV-2 re-infection in this group. A limitation of this approach is that some participants might suffer from persisting COVID-19 symptoms (i.e. long-COVID). In particular loss of smell has been shown to persist for several weeks in a certain proportion of COVID-19 patients [17]. If we had excluded seropositive participants who already reported this symptom at baseline, the effect would have even been more pronounced. Worryingly, re-infections with phylogenetically different SARS-CoV-2 strains are increasingly being reported [18]. A recent report documented severe reinfection with the “new variant” VOC-20...

    Results from TrialIdentifier: No clinical trial numbers were referenced.

    Results from Barzooka: We found bar graphs of continuous data. We recommend replacing bar graphs with more informative graphics, as many different datasets can lead to the same bar graph. The actual data may suggest different conclusions from the summary statistics. For more information, please see Weissgerber et al (2015).

    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.

    Results from scite Reference Check: We found no unreliable references.

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  3. Version published to 10.1101/2021.06.09.21258422v1 on medRxiv