What is it about?
Early in the COVID-19 pandemic, it was clear that men were more often severely ill and died more than women, even after accounting for age. At the same time, we were reviewing infections caused by BCG, the live bacterium instilled into the bladder to treat early bladder cancer, which can occasionally spread and cause disease (BCGitis). Among 243 published BCGitis cases, only three occurred in women - a 49-to-1 ratio that cannot be explained only by the higher frequency of bladder cancer in men or by catheter trauma. In this letter we propose that differences in interferon-gamma, a key immune signal against intracellular infections, may underlie both observations: men produce lower levels of interferon-gamma, which could favour both BCG dissemination and severe COVID-19.
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Photo by National Institute of Allergy and Infectious Diseases on Unsplash
Why is it important?
Understanding why men and women respond differently to infections can guide research on risk factors and treatments. Our hypothesis links two very different clinical situations through a common immune mechanism and suggests that interferon pathways and sex-related immune differences deserve further study in COVID-19 and in BCG-related infections.
Perspectives
Sometimes connections appear by chance: we were working on BCG complications when the pandemic began, and the same striking male predominance caught our eye. This letter is an example of how clinical curiosity can generate hypotheses worth testing.
Professor Stefano Di Bella
Universita degli Studi di Trieste
Read the Original
This page is a summary of: Interferon: The invisible link in the physiopathology of COVID‐19 and BCGitis?, Scandinavian Journal of Immunology, August 2020, Wiley,
DOI: 10.1111/sji.12939.
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