BMC Medicine (Oct 2021)

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

  • Philipp Kohler,
  • Sabine Güsewell,
  • Marco Seneghini,
  • Thomas Egger,
  • Onicio Leal,
  • Angela Brucher,
  • Eva Lemmenmeier,
  • J. Carsten Möller,
  • Philip Rieder,
  • Markus Ruetti,
  • Reto Stocker,
  • Danielle Vuichard-Gysin,
  • Benedikt Wiggli,
  • Ulrike Besold,
  • Stefan P. Kuster,
  • Allison McGeer,
  • Lorenz Risch,
  • Andrée Friedl,
  • Matthias Schlegel,
  • Pietro Vernazza,
  • Christian R. Kahlert

DOI
https://doi.org/10.1186/s12916-021-02144-9
Journal volume & issue
Vol. 19, no. 1
pp. 1 – 10

Abstract

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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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