Trained Immunity, BCG and SARS-CoV-2 General Outline and Possible Management in COVID-19

Abstract

The Bacillus Calmette–Guérin (BCG) vaccine has been in use for over 100 years. It protects against severe, blood-borne forms of tuberculosis. Observations indicate that it also increases immunity against other diseases. The mechanism responsible for this is trained immunity, an increased response of non-specific immune cells in repeated contact with a pathogen, not necessarily of the same species. In the following review, we present the current state of knowledge on the molecular mechanisms responsible for this process. We also seek to identify the challenges facing science in this area and consider the application of this phenomenon in managing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic.

Coronavirus Disease Pathophysiology: Biomarkers, Potential New Remedies, Comorbidities, Long COVID-19, Post Pandemic Epidemiological Surveillance

“…During the COVID-19 breakout, when humanity was immune-less against SARS-CoV-2, and there was no proven remedy, many researchers postulated using trained immunity in the fight against the virus [2][3][4]. The review article in our Special Issue by Zapolnik, Kmiecik, Mazur, and Czajka developed this idea further and discussed in detail the potential use of BCG-vaccine-induced trained immunity as a possible tool in the management in COVID-19 [5]. The trained immunity could be a partial solution if vaccines against SARS-CoV-2 appeared inefficient.…”

“…This, in turn, could favor mutations, which theoretically could create more dangerous forms of Mycobacterium. The review article by the Polish team [5] discussed all the facets of the potential BCG use in this and future pandemics.…”