Bacille Calmette-Guérin (BCG) vaccine and potential cross-protection against SARS-CoV-2 infection — Assumptions, knowns, unknowns and need for developing an accurate scientific evidence base

https://doi.org/10.1016/j.ijid.2021.03.060Get rights and content
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Highlights

  • BCG-derived peptide develops high reactivity to SARS-CoV-2.

  • BCG vaccine increases nonspecific immune responses through adjuvant effect.

  • BCG effect could be harnessed as cross protection against severe forms of COVID-19.

  • Clinical trials for the effectiveness of BCG vaccination against COVID-19 are needed.

Abstract

After a century of controversies on its usefulness in protection against TB, underlying mechanisms of action, and benefits in various groups and geographical areas, the BCG vaccine is yet again a focus of global attention- this time due to the global COVID-19 pandemic caused by the novel severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Recent studies have shown that human CD4+ and CD8+ T-cells primed with a BCG-derived peptide developed high reactivity to its corresponding SARS-CoV-2-derived peptide. Furthermore, BCG vaccine has been shown to substantially increase interferon-gamma (IFN-g) production and its effects on CD4+ T-cells and these non-specific immune responses through adjuvant effect could be harnessed as cross protection against severe forms of COVID-19.The completion of ongoing BGG trials is important as they may shed light on the mechanisms underlying BCG-mediated immunity and could lead to improved efficacy, increased tolerance of treatment, and identification of other ways of combining BCG with other immunotherapies.

Keywords

SARS-CoV-2
Tuberculosis
BCG
Immunity
COVID-19
Protection

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All authors contributed equally.