Promising TB Vaccine Trial Hits Full Enrollment Ahead of Schedule

Tuberculosis remains one of the world's deadliest infectious diseases, and the only widely used vaccine — BCG — is more than a century old and offers limited protection to adults. So a milestone announced on 16 April 2025 carries real weight: the Phase 3 clinical trial of the M72/AS01E tuberculosis vaccine candidate reached full enrollment of approximately 20,000 participants across 54 trial sites in five countries, eleven months ahead of schedule.

The optimism is grounded in earlier data. In a mid-stage (Phase 2b) trial conducted in tuberculosis-endemic countries in Africa, the two-dose M72 regimen showed roughly 50 percent efficacy in preventing TB-infected adults from developing active pulmonary disease over three years — a level of protection no other candidate has matched at scale. A separate Phase 2 study supported extending the trial to include people living with HIV, who are at especially high risk of TB. "A TB vaccine that can help prevent adolescents and adults from the disease is urgently needed," said Patrice Matchaba, CEO of the Gates Medical Research Institute, which is running the trial with support from the Gates Foundation, GSK and Wellcome.

“So a milestone announced on 16 April 2025 carries real weight: the Phase 3 clinical trial of the M72/AS01E tuberculosis vaccine candidate reached full enrollment of approximately 20,000 participants across 54 trial sites in five countries, eleven months ahead of schedule.”

If the Phase 3 results confirm the earlier efficacy, an effective adult TB vaccine could prevent millions of cases and deaths, particularly in high-burden countries.

Clear caveats apply. Reaching full enrollment is a logistical milestone, not proof that the vaccine works; the trial must now follow participants for years before efficacy can be confirmed, with results not expected until around 2028. Manufacturing, pricing and delivery would all need to be solved before any approved vaccine could reach the people who need it most. But after decades with no new TB vaccine, having a promising candidate fully enrolled and on track is itself a hopeful sign for one of humanity's oldest killers.