Why is TB still killing people?

Episode Summary

Executive Summary: The episode examines why tuberculosis remains one of the world’s deadliest infectious diseases despite a century of vaccination and decades of antibiotics. Experts explain that BCG mainly protects infants from severe TB, treatment is long and complex, the bacterium can hide in immune cells, drug resistance is rising, and poverty plus weak health systems sustain transmission. Promising new vaccines may change the outlook.

Main Topics: Why TB still kills millions (Priority: 5/5): The show frames TB as a persistent global health crisis, contrasting its relative rarity in the UK with its ongoing burden in high-incidence countries and its ability to cause severe illness and death. Limits of the BCG vaccine (Priority: 5/5): Historical and scientific context shows BCG was a milestone but offers incomplete protection, especially in adults, though it still helps protect babies from TB meningitis. Lengthy, difficult treatment and drug resistance (Priority: 5/5): TB requires multiple antibiotics for months, making adherence hard and creating opportunities for resistance; patients also face stigma and practical barriers to completing treatment. How TB survives in the body (Priority: 4/5): Researchers explain TB’s ability to persist in macrophages, remain quiescent or dynamic in hidden states, and evade elimination, which complicates cure and prevention. New vaccine development (Priority: 4/5): The episode highlights ongoing vaccine research, especially the M72 candidate, which showed a promising efficacy signal and is now in phase 3 trials. Social determinants of TB (Priority: 5/5): Experts emphasize that TB is strongly linked to poverty, nutrition, housing, sanitation, and access to healthcare, meaning biomedical solutions alone are insufficient.

Key Arguments: BCG is an important milestone, but its protection is limited and wanes over time, especially in adults. TB remains prevalent because treatment is long, uses multiple antibiotics, and therefore is hard to complete and vulnerable to resistance. The bacterium’s biology is unusually complex: it grows slowly, hides in immune cells, and can persist in poorly understood states. A truly effective TB cure will likely require better vaccines, better drugs, and faster diagnostics. High-burden settings such as South Africa are essential for vaccine trials because impact can be measured against many cases. TB is not only a biomedical problem; poverty, housing, nutrition, and healthcare access are central drivers of continued transmission and mortality.

Data Points: Annual TB deaths: over 1 million - Global scale of TB mortality mentioned in the discussion. Latent TB prevalence: about 1 in 4 people worldwide - Estimate used to illustrate how widespread TB infection is. BCG age protection: works mainly in early life - Experts said the vaccine protects children, especially against TB meningitis, but protection wanes. TB treatment duration: at least 6 months - Standard treatment described as prolonged and burdensome. Number of antibiotics in treatment: at least 3, sometimes 4 or more - Used to explain complexity of TB therapy. Janet’s weight loss: 80 kg to 64 kg - Patient in Nairobi described severe illness before diagnosis and treatment. TB cases in South Africa 20 years ago: more than 600,000 per year - Used to explain why South Africa is a key site for vaccine research. M72 trial phase 2 efficacy signal: more than 50% - Promising result for preventing disease in infected people. M72 phase 3 enrollment: 20,000 people - Large confirmatory trial now underway. Earlier M72 phase 2 sample size: about 3,500 people - The smaller study that produced the initial efficacy signal. Projected impact of a successful M72 vaccine: 75 million cases averted; 8.5 million deaths prevented over 25 years - Projected public-health benefit if efficacy holds. Age of George Orwell at death: 46 - Opening anecdote to underscore TB’s historical lethality.

Pivotal Quotes: "the number of cases that you get of TB per year clearly shows that the vaccine doesn't really work" — Max Gutierrez: Explaining why BCG is inadequate as a standalone solution, especially for adults. "TB is a disease of poverty, socio-economic condition." — Unnamed expert quoted in the closing section: Summarizing the episode’s conclusion that social conditions are central to TB control. "It makes me sad. It makes me angry." — Angelique Luabia Kanikani: Reacting to the death of her uncle from TB and the avoidable delay in diagnosis and treatment.

Implications: TB will not be beaten by one intervention alone. The episode suggests progress depends on better vaccines, shorter and stronger drugs, earlier diagnosis, and major improvements in living conditions and healthcare access.