On June 28, the Bill and Melinda Gates Foundation announced that they would contribute $400 million to the late-stage trial for a new Tuberculosis vaccine. The M72 vaccine, if approved, will be the first new TB vaccine in 100 years. According to the WHO, 1.6 million people died from TB in 2021 and 80% of cases and deaths were in developing countries. Therefore, this vaccine could have an enormous impact on the developing world and people in poverty.

How it Works

The M72 vaccine is a subunit vaccine, meaning that it contains two antigens that are found on the surface of TB bacteria. These antigens, when recognized by the body, provoke an immune response to the TB bacteria. The antigens were specifically selected by the vaccine developer, GSK, for having such a solid ability to provoke this immune response against TB. In 2019, early trials of the M72 TB vaccine showed it to be 54% effective in adults with latent TB, a group that no vaccine has worked on before.

Latent TB refers to the period after initial infection with the TB bacteria but before the active TB stage begins. When initial infection occurs, the body mounts an immune response, but some bacteria survive this. During the latent stage, these surviving bacteria multiply, and patients usually do not experience any symptoms. This stage can last months or years until the immune system can no longer control the bacteria, at which point the active stage of TB begins.

The only existing TB vaccine, the BCG vaccine, is made from a weakened strain of TB. While it is effective at combating meningitis and TB in children, it does not prevent primary infection or the reactivation of TB bacteria after the latent stage. Therefore, unlike the M72, it is not effective in adults with latent TB.

Funding the Trial

Despite this vaccine being the first to affect people with latent TB, GSK decided that it was not financially viable to pursue further trials because of the 54% efficacy. However, two charities have stepped in to keep the vaccine alive.

The stage three trial that the Bill and Melinda Gates Foundation is making a contribution toward will cost $550 million. The Foundation’s $400 million donation, its largest-ever investment in a single project, will be combined with a further $150 million from the Wellcome Trust to make up this total. The trial will take place at a dozen locations across Africa and Asia, selected for their unusually high rates of latent TB infection so that scientists can efficiently determine if the vaccine prevents active TB from beginning. The trial will involve around 26,000 participants and will take four to six years to complete.

However, the investment from charities alone may not be enough. The vaccine could still need a commercial partner, something that the Foundation hopes to secure in the next 12 months. There is concern about this, since the lack of a market for the vaccine in the developed world may discourage many vaccine makers. However, Indian vaccine producers have expressed interest, since the jab would significantly impact their country, where it’s estimated 504,000 people died from TB in 2021.

The Bottom Line

According to the WHO, if the trial proves that the new TB vaccine really does have a 50% efficacy rate, it could save up to 8.5 million lives by 2050, with the most significant impact being in developing countries and for people living in poverty. Additionally, it could prevent the prescription of 42 million courses of antibiotic treatment, and therefore hopefully combat TB’s antibiotic resistance.

With the potential to be the first new vaccine in 100 years, the M72 jab is promising. However, the fight against TB is not yet over. Despite the lack of burden in wealthier countries, this vaccine still needs attention in the developed world, particularly from vaccine producers, so that, if it proves viable, it can help people in poverty around the world.

– Lily Cooper

Photo: Flickr