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Comment
. 2021 Jan 15;39(3):460-462.
doi: 10.1016/j.vaccine.2020.12.026. Epub 2020 Dec 13.

BCG vaccine: Worrying proposal for COVID-19

Emanuel Sarinho  1 , Ekaterini Goudouris  2 , Dirceu Solé  3
Affiliations
Comment

BCG vaccine: Worrying proposal for COVID-19

Emanuel Sarinho et al. Vaccine. .

Abstract

Bacille Calmette-Guérin (BCG) vaccine is proven to be effective in protecting against severe tuberculosis. It has been suggested to be able to exert a non-specific beneficial effect as protection against other infectious diseases. The duration of protection against tuberculosis is estimated to be from 10 to 15 years, but the duration of the protection against other infections is not known, maybe up to 20 years, maybe much shorter than that. We don't know it for sure. BCG induced trained immunity paradigm is based on experimental models, cohort studies with low number of individuals, and some epidemiological data in which other possible interfering factors are not controlled. The titles and scopes of scientific articles should be cautiously considered as they can promote indications of getting vaccinated or revaccinated with BCG, before its effectiveness is confirmed and recommendations are published. Besides, revaccination with BCG can put at serious risk patients with primary or secondary immunodeficiency. Maybe BCG vaccine is effective in preventing COVID-19 deaths or reducing its severity, but may the effect of this vaccine be relevant even with poor health politics and assistance? It is very difficult to compare the epidemiologic data about COVID-19 in different countries. There are countless factors, mainly social and related to the healthcare system, which can be more decisive than the hypothesis of trained immunity induced by BCG. Until now, we can say that BCG's protective role is, at least, insufficient, given many other factors that corroborate SARS-CoV-2 infection and/or its severity.

Keywords: BCG vaccine; COVID-19; Immunity; Innate.

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Conflict of interest statement

Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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