Bacillus Calmette-Guerin Vaccine and Nonspecific Immunity.
Am J Med Sci
; 361(6): 683-689, 2021 06.
Article
in English
| MEDLINE | ID: covidwho-1118316
ABSTRACT
Bacillus Calmette-Guerin (BCG) vaccine is one of the most widely used vaccines in the world. It protects against many non-mycobacterial infections secondary to its nonspecific immune effects. The mechanism for these effects includes modification of innate and adaptive immunity. The alteration in innate immunity is through histone modifications and epigenetic reprogramming of monocytes to develop an inflammatory phenotype, a process called "trained immunity." The memory T cells of adaptive immunity are also responsible for resistance against secondary infections after administration of BCG vaccine, a process called "heterologous immunity." Bacillus Calmette-Guerin vaccine is known to not only boosts immune responses to many vaccines when they are co-administered but also decrease severity of these infections when used alone. The BCG vaccine by itself induces a TH1 type response, and its use as a vector has also shown promising results. This review article summarizes the studies showing effects of BCG vaccines on various viral infections, its role in enhancing vaccine responses, the mechanisms for this protective effect, and information on its effect on COVID-19.
Keywords
Full text:
Available
Collection:
International databases
Database:
MEDLINE
Main subject:
BCG Vaccine
/
Adaptive Immunity
/
COVID-19
/
Immunity, Innate
Type of study:
Observational study
/
Prognostic study
Topics:
Vaccines
Limits:
Humans
Language:
English
Journal:
Am J Med Sci
Year:
2021
Document Type:
Article
Affiliation country:
J.amjms.2021.03.003
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