Fig. 1: Trained immunity antiviral host defence.
From: BCG-induced trained immunity: can it offer protection against COVID-19?
a | Bacillus Calmette–Guérin (BCG) vaccination has been shown to protect against multiple viral pathogens, including respiratory syncytial virus (RSV), influenza A virus and herpes simplex virus type 2 (HSV2). Will it protect against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)? b | Trained immunity leading to enhanced innate immune responses to different pathogens after a vaccination is mediated by metabolic and epigenetic rewiring in innate immune cells, which leads to increased gene transcription and improved host defence. c | Trained immunity as a tool for enhancing population immunity during a pandemic ahead of the availability of a specific vaccine. TNF, tumour necrosis factor.
