The surprising power of a century-old vaccine for tuberculosis

Scientists in Canada believe they may be closer to understanding a positive additional benefit associated with Bacillus Calmette Guérin (BCG), a century-old vaccine for tuberculosis. It turns out the TB jab has a surprising superpower: flu prevention. But how, precisely, it protects against influenza has been something of a mystery.

Now, as a new study by the Research Institute of the McGill University Health Centre (RI-MUHC) is shedding light on understanding of respiratory immune responses, scientists say they discovered a surprising feature of the body’s reaction to BCG.

The study, published in the journal Nature Immunology, reveals a previously unknown mechanism that extends the vaccine’s shield to combat influenza A virus – the most prevalent flu strain.

‘The immune interactions involved here can ‘train’ the lungs, which are frequently exposed to infectious agents in the environment,’ said lead author Maziar Divangahi, a pulmonary immunologist, a senior scientist at the RI-MUHC, and a Professor of Medicine at McGill University. ‘If we can map out the protective immune pathways involved in the lungs, this will revolutionise our conceptual and clinical approaches in developing vaccines against infections, including emergent respiratory viruses.’

The discovery paves the way for future work to assess whether BCG could be used to prevent other emergent viruses. Notably, research on the vaccine’s protection against COVID-19 has had promising results.