Why Tuberculosis Still Kills Millions Despite a Vaccine and Effective Treatment

Despite the existence of a vaccine and effective treatment for over a century, tuberculosis continues to claim the lives of millions each year. In 2024, the World Health Organization (WHO) reported that the disease killed an estimated 1.23 million people worldwide, with another 10.7 million falling ill to the condition. While the incidence rate did decline by 1.7% from 2023 to 2024, marking the first year-on-year drop since the COVID-19 pandemic, progress remains too slow.

The global TB incidence rate had fallen 12.3% between 2015 and 2024, but this still falls short of the WHO's target of a 50% reduction by 2025.

The scientific tools against TB, such as the BCG vaccine developed in the early 20th century and the discovery of streptomycin as the first effective antibiotic in 1943, have been instrumental in treating the disease. However, these tools have not managed to eradicate TB. The BCG vaccine, being the only licensed TB vaccine, provides moderate protection against severe forms of the disease in infants and young children. Yet, there is currently no effective vaccine for adults.

The effectiveness of treatment hinging on sustained access to diagnosis and medicines is crucial. When health systems fail to detect cases or when patients cannot access care, TB continues to spread. The WHO estimates that around one-quarter of the world's population has been infected with TB bacteria, with most infected individuals never developing active disease.

However, those who do develop active TB have a 5% to 10% lifetime risk, which increases due to factors like HIV infection, malnutrition, diabetes, and tobacco use.

Living conditions also play a significant role in TB transmission. Overcrowded and poorly ventilated spaces raise the risk of exposure, while poverty can impede timely diagnosis and treatment, exacerbating other risk factors for active disease. Despite the progress made, a significant diagnostic gap remains. In 2024, health authorities reported 8.3 million newly diagnosed TB cases, corresponding to 78% of the estimated 10.7 million people who contracted the disease.

This left approximately 2.4 million individuals either undiagnosed or not officially reported to national authorities.

Drug resistance also compounds the issue, with the WHO estimating that 390,000 people developed multidrug-resistant or rifampicin-resistant TB in 2024. However, only about 40% of those with drug-resistant disease received treatment. Historically, improvements in living conditions, nutrition, and housing have contributed to declines in TB transmission outside of medical treatment.

However, the Americas have moved in a counterproductive direction from the global trend. Between 2015 and 2024, the Americas saw a 13% increase in TB incidence, while the global rate declined by 12.3%. Between 2015 and 2024, the region's TB incidence increased by 13%, compared to a 12.3% global decline over the same period.