Tuberculosis kills more than a million people every year. It’s the world’s leading cause of death from a single infectious agent. This is despite the fact that we've had a cure for TB since the 1940s and a vaccine that’s over 100 years old. So why is TB still causing so many people to die?

That’s what CrowdScience listener John in Tanzania wants to know, and presenter Marnie Chesterton is on the case. Over in Paris, she’s joined by Dr Claas Kirchhelle, historian of science, medicine and technology at French National Institute of Health and Medical Research (INSERM) to look into the history and efficacy of the vaccine, known as BCG.

As Dr Maximiliano Gutierrez, Associate Research Director at the Francis Crick Institute adds, the BCG is both effective and ineffective, protecting children well against severe TB, but offering inconsistent and often poor protection in adults. He also explains that antibiotics are a trickier treatment than we might expect. Over in Kenya’s Kibera slums, Janet tells us her about her experience of the drugs first hand.

Dr Dany Beste, Senior Lecturer In Microbial Metabolism, University of Surrey, has been described as a dietician of mycobacterium tuberculosis. She explains the limitations of our knowledge of this bacterium, and why it is proving such a tricky customer.

And since a better vaccine is the main hope for reducing the TB burden, Professor Angelique Luabeya Kany Kany, Chief Research Officer at University of Cape Town, shares her hopes for the first new alternative vaccine in 100 years: m72. Large phase 3 clinical trials are currently underway, and, if successful, could prevent millions of cases, and deaths a year.

Presenter: Marnie Chesterton

Producer: Marnie Chesterton

Editor: Ben Motley

(Photo: Doctor with vial of the doses vaccine for BCG Bacillus Calmette Guerin against tuberculosis disease. Medicine and health care concept - stock photo - Credit: angelp via Getty Images)