Surprising Benefits of Century-old Bacille Calmette-Guérin (BCG) Vaccine

Broadly protective nature of the 100-year-old Bacille Calmette-Guérin (BCG) vaccine has been finally decoded by a study at the Boston Children's Hospital, published in the journal Cell Reports. The century-old BCG vaccine is a widely accepted preventive measure against tuberculosis. Recently, several lines of evidence also shed light on its efficacy against COVID-19.

“A growing number of studies show that BCG vaccine protects against unrelated infections. It’s critical that we learn from BCG to better understand how to protect newborns. BCG is an ‘old school’ vaccine — it’s made from a live, weakened germ — but live vaccines like BCG seem to activate the immune system in a very different way in early life, providing broad protection against a range of bacterial and viral infections. There’s much work ahead to better understand that and use that information to build better vaccines for infants,” says Ofer Levy, MD, PhD, the study’s senior investigator.

Every year, around 100 million newborns are immunized globally by BCG vaccine due to its surprisingly protective nature to infants (against TB and multiple bacterial & viral infections), especially in endemic areas.

Broad Efficacy of BCG Vaccine

However, the reason behind the broad protective nature of the vaccine has been questioned. Hence, the study team analyzed the blood samples of newborns immunized with BCG, using a powerful “big data” approach.

It was found that the BCG vaccine helps induce specific changes in metabolites and lipids that correlate with innate immune system response — changes in cytokine production, thereby providing clues toward making effective future vaccines for the vulnerable populations.

“We now have some lipid and metabolic biomarkers of vaccine protection that we can test and manipulate in mouse models. We studied three different BCG formulations and showed that they converge on similar pathways of interest. Reshaping of the metabolome by BCG may contribute to the molecular mechanisms of a newborn’s immune response,” says First author Joann Diray Arce, PhD.

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Source-Medindia