Cell Reports (Mar 2022)

BCG vaccination provides protection against IAV but not SARS-CoV-2

  • Eva Kaufmann,
  • Nargis Khan,
  • Kim A. Tran,
  • Antigona Ulndreaj,
  • Erwan Pernet,
  • Ghislaine Fontes,
  • Andréanne Lupien,
  • Patrice Desmeules,
  • Fiona McIntosh,
  • Amina Abow,
  • Simone J.C.F.M. Moorlag,
  • Priya Debisarun,
  • Karen Mossman,
  • Arinjay Banerjee,
  • Danielle Karo-Atar,
  • Mina Sadeghi,
  • Samira Mubareka,
  • Donald C. Vinh,
  • Irah L. King,
  • Clinton S. Robbins,
  • Marcel A. Behr,
  • Mihai G. Netea,
  • Philippe Joubert,
  • Maziar Divangahi

Journal volume & issue
Vol. 38, no. 10
p. 110502

Abstract

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Summary: Since the vast majority of species solely rely on innate immunity for host defense, it stands to reason that a critical evolutionary trait like immunological memory evolved in this primitive branch of our immune system. There is ample evidence that vaccines such as bacillus Calmette-Guérin (BCG) induce protective innate immune memory responses (trained immunity) against heterologous pathogens. Here we show that while BCG vaccination significantly reduces morbidity and mortality against influenza A virus (IAV), it fails to provide protection against severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In contrast to IAV, SARS-CoV-2 infection leads to unique pulmonary vasculature damage facilitating viral dissemination to other organs, including the bone marrow (BM), a central site for BCG-mediated trained immunity. Finally, monocytes from BCG-vaccinated individuals mount an efficient cytokine response to IAV infection, while this response is minimal following SARS-CoV-2. Collectively, our data suggest that the protective capacity of BCG vaccination is contingent on viral pathogenesis and tissue tropism.

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