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

Cell reports

Authors: 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

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.

Copyright © 2022 The Author(s). Published by Elsevier Inc. All rights reserved.

PMID: 35235831

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