Every 25 seconds, tuberculosis (TB), a bacterial infection that attacks the lungs, claims another victim. In 2023, 1.25 million people died from TB, making it once again the world’s deadliest infectious disease after three years of COVID-19 claiming that title. Without a more effective vaccine, the world will soon see even more deaths from TB due to the rise of drug-resistant strains of the disease.
As a pediatrician and researcher in Johannesburg, South Africa, Dr. Lee Fairlie has seen more than her share of TB over the years. “For many reasons, TB still remains a huge problem here,” she says. One of those reasons is that South Africa has a large population of people living with HIV, and TB is the leading cause of death among people with HIV. “We know that TB and HIV coexist very happily together, unfortunately,” Dr. Fairlie says.
Despite the urgency of controlling TB, progress has been slow. While the Bacille Calmette-Guérin (BCG) vaccine against TB, developed in 1921, “is still given to newborns and still really works well in younger children,” says Dr. Fairlie, it provides little protection for adolescents and adults, who make up most TB cases. And for a long time, no new TB vaccine has been on the horizon.
“I’m not really somebody who easily gives up,” says Dr. Fairlie. “It is about just putting one foot in front of the other and carrying on.” Now, she and her colleagues may be on the verge of witnessing a breakthrough. Her clinical research team is one of the sites conducting the a landmark M72/AS01E tuberculosis vaccine trial, sponsored by the Gates Medical Research Institute and funded by the Gates Foundation and Wellcome, which includes sites across four African countries (including South Africa) and Indonesia. Initially developed by GSK with collaboration from Aeras and the International AIDS Vaccine Initiative, M72 could potentially be the first new TB vaccine in more than a century, and the first-ever to help protect adults and adolescents from the disease.
The clinical trial has enrolled 20,000 people and is still in its early stages, but M72’s performance in previous trials has filled Dr. Fairlie and her team with hope. An earlier study, published in 2019, reported nearly 50% efficacy after three years in preventing TB-infected adults from developing active disease, which would make them sick and also contagious. “We haven’t had results like that since basically BCG,” says Dr. Fairlie, “which really is a long time ago.” A separate Phase 2 study sponsored by Gates Medical Research Institute study also found the M72 vaccine has an acceptable safety profile and elicited strong responses for people living with HIV.
If M72 shows similar results in this final stage of testing and is ultimately approved, it could permanently knock TB out of its top spot on the list of infectious killers. The World Health Organization could potentially prevent 76 million new TB cases over the next quarter-century.
While the results of the current trial are still several years away, Dr. Fairlie is optimistic. “[G]rowing up in a country like South Africa with so many socioeconomic inequities that really permeate through health, having an opportunity to make a massive impact in terms of preventing TB and all the hardships that go with it is incredibly exciting,” she says.
Read the foundation's press release announcing funding to advance the M72 vaccine candidate.
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