BCG-induced trained immunity: can it offer protection against COVID-19?

Bacillus Calmette–Guérin (BCG) vaccination has been reported to decrease susceptibility to respiratory tract infections, an effect proposed to be mediated by the general long-term boosting of innate immune mechanisms, also termed trained immunity. Here, we discuss the non-specific beneficial effects of BCG against viral infections and whether this vaccine may afford protection to COVID-19. Could the BCG vaccine be used to bridge the gap until a specific COVID-19 vaccine is developed? Luke O’Neill and Mihai Netea discuss the science behind this approach.

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