Samples of lung fluid are used to diagnose tuberculosis ANDY CRUMP, TDR, WHO/SCIENCE PHOTO LIBRARY

An experimental tuberculosis (TB) vaccine is partially effective at preventing a dormant infection from progressing to active disease. If the results hold up in larger trials, the treatment could save millions of lives.

TB is one of the top 10 causes of death worldwide, claiming 1.5 million lives in 2018. The BCG vaccine is used to prevent the disease in children, but there is no effective vaccine for adults.

About a quarter of the world’s population has latent TB, which means they are infected with the bacteria but it is lying dormant. They don’t experience symptoms and can’t transmit the disease. About 5 to 10 per cent of people with latent infection go on to develop active disease.


The new vaccine, known as M72/AS01 E , has been developed by pharmaceutical firms GlaxoSmithKline and Aeras. The trial involved in 3575 adults in Kenya, South Africa and Zambia with latent tuberculosis infection, half of whom were given two doses of the vaccine and the other half of whom had a placebo.

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After three years, there were half as many cases of active disease in the vaccine group as the placebo group. An efficacy of 50 per cent is low compared with most established vaccines, but given the prevalence of TB and the shortage of other preventative treatments, such a vaccine could have a big effect on the number of cases.

Larger trials will be needed to better assess the efficacy of the vaccine before it can be licensed for use, but these results are seen as very promising.

“This is the first vaccine that has ever shown protection in previously infected individuals and so offers the potential for protection of vast numbers of people in endemic countries,” says Barry Bloom at Harvard School of Public Health, who wasn’t involved in the study.

“Even if only 50 per cent effective, with 10 million new cases and 1.4 million deaths annually, the number of lives that could be saved would be great.”

Journal reference: New England Journal of Medicine, DOI: 10.1056/NEJMoa1909953