key: cord-0790913-zaba3jcw
authors: Patella, Vincenzo; Florio, Giovanni; Brancaccio, Raffaele; Delfino, Gabriele
title: Could anti‐tubercular vaccination protect against COVID‐19 infection?
date: 2020-07-09
journal: Allergy
DOI: 10.1111/all.14443
sha: 37c2dc2836a51339f4b3fb6f72efeb7b35ee7c6e
doc_id: 790913
cord_uid: zaba3jcw

We have read with great attention the kind contribute by C. Ozdemir et al.,about the possible effects of tuberculosis vaccine with Calmette-Guérin Bacillus (BCG) on the course of COVID-19 pandemics[1]. We agree, because our group has been working for the last few months on thishypothesis, with a different approach,over the ability of BCG to provide protection against COVID-19. Several studies, as also reportedby Redelman-Sidi, G., are currently ongoing to determine the effect of BCG vaccination on outcomes from COVID-19, including in two high-risk populations [2]. The countries without universal vaccination policies (i.e.: Italy, Netherlands, United States) would seemto be hit more severely against COVID-19, than in countries with universal vaccination policies and for a long time with BCG.Since 1975, BCG vaccination policy in Sweden changed from routine vaccination of all newborn infants to selective vaccination of groups at higher risk [3], andSpain did the same, but not Portugal(Fig.1).

demics. 1 We agree, because our group has been working for the last few months on this hypothesis, with a different approach, over the ability of BCG to provide protection against COVID-19. Several studies, as also reported by Redelman-Sidi, G., are currently ongoing to determine the effect of BCG vaccination on outcomes from COVID-19, including in two high-risk populations. 2 The countries without universal vaccination policies (ie, Italy, Netherlands, United States) would seem to be hit more severely against COVID-19, than in countries with universal vaccination policies and for a long time with BCG.

Since 1975, BCG vaccination policy in Sweden changed from routine vaccination of all newborn infants to selective vaccination of groups at higher risk, 3 and Spain did the same, but not Portugal (Figure 1 ). 

When regulatory and disclosure screens are filled in, the app asks the questions to get, in unnamed, the data of BCG vaccination in doctor population high mortality rate from COVID-19, as protective vaccination against BCG is mandatory in Portugal while in Spain it is not ( Figure 2 ). In order to respond to their question about BCG vaccination effecting the spread and severity of COVID-19, we argue that the BCG vaccination seems to induce a immune response also against other infectious agents, 7 acting as an immune enhancer of innate immune system components. This immunological phenomenon was extensively studied, especially the induction of "non-antigen-specific immunological memory" in innate immunity cells as macrophages, monocytes, and NK cells. After BCG stimulation, these cells undergo an epigenetic reprogramming of some transcription factors; promoters of cytokine genes are de-phased or de novo created. Excluding any influence due to pollution and/or climate change, 8 this epigenetic remodeling is maintained even after the disappearance of the primary stimulus ("nonspecific immunological memory of the antigen"), giving the cell the ability to respond more powerfully to the next stimulus, although not related to previous stimuli. The improved response capacity of these enhanced cells seems to be linked essentially to specific cytokine secretion profiles that promote a more effective elimination of any infection; in particular, IL-1β has been identified as main cytokine effecting to reduce viremia in case of secondary viral stimuli. 9 We identified the Italian Medical Class as a study cohort because they underwent BCG vaccination for regulatory devices, and in parallel is the subject most exposed to infection. Therefore, an observational study aimed at understanding whether there is an epidemiological relationship between vaccination with BCG and COVID-19 was approved on March 31, 2020, by an independent Ethical Committee. The aim of this study is to assess the ability and readiness to respond to viral infection by doctors who have been 

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