The century-old Bacille Calmette-Guérin (BCG) vaccine against tuberculosis is one of the world’s oldest and most widely used vaccines, used to immunize 100 million newborns every year. Given in countries with endemic TB, it has surprisingly been found to protect newborns and young infants against multiple bacterial and viral infections unrelated to TB. There’s even some evidence that it can reduce severity of COVID-19.

Current treatment regimens for Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, are long, complex, and hard for people to sustain. Moreover, the bacteria often develop drug resistance, and many people harbor multi-drug-resistant strains. In 2018 alone, nearly 1.5 million people died from tuberculosis worldwide.