Title:Tuberculosis, BCG Vaccination, and COVID-19: Are They Connected?
Volume: 22
Issue: 12
Author(s): Kellen Christina Malheiros Borges, Adeliane Castro da Costa, Lília Cristina de Souza Barbosa, Kaio Mota Ribeiro, Laura Raniere Borges dos Anjos, André Kipnis and Ana Paula Junqueira-Kipnis*
Affiliation:
- Institute of Tropical Pathology and Public Health, Federal University of Goiás, Goiânia, Goiás, Brazil
Keywords:
BCG, SARS-CoV-2, innate immunity, heterologous vaccine effects, natural killer cells, macrophages, tuberculosis.
Abstract: Evidence from multiple scientific studies suggests that the Bacillus Calmette–Guérin (BCG)
vaccine, widely used worldwide as a preventive measure against tuberculosis, also offers crossprotection
against other pathogens. This review aimed to gather data from research that studied the
mechanisms involved in the immunological protection induced by the BCG vaccine, which may be
important in the control of viral infections, such as COVID-19. Through a literature review, we compiled
information about the different BCG strains used worldwide, as well as the responses and protection
elicited by them. We commented on the mechanisms of immune response to Severe Acute Respiratory
Syndrome Coronavirus 2 (SARS-CoV-2), and we discussed the possibility of cross-protection of
different BCG strains on the control of COVID-19. Due to the immunomodulatory properties of BCG,
some BCG strains were able to induce an effective cellular immune response and, through epigenetic
modifications, activate cells of the innate immune system, such as monocytes, macrophages and natural
killer cells, which are crucial for the control of viral infections. Although several vaccines have already
been developed and used in an attempt to control the COVID-19 pandemic, some BCG vaccine
strains may help stimulate the basal defences against these pathogens and can be used as additional defences
in this and future pandemics.