LONDON: A lack of funding could delay late-stage trials of the first new vaccine against tuberculosis for more than a century, warned Bill Gates, whose foundation is backing the development of the shot.

The Microsoft co-founder turned philanthropist said there were a raft of promising innovations in the fight against TB, the world’s biggest infectious disease killer, but that more funding was essential.

"The failure to fund these things… like we can’t go full speed ahead on these vaccine trials - that’s a huge mistake," he told Reuters in an interview on Monday.

The Bill and Melinda Gates Foundation is the largest funder of the battle against TB, he said, and the work on the M72/AS01 vaccine, originally developed by GSK and the Gates-backed non-profit Aeras, is now being led by the Bill and Melinda Gates Medical Research Institute.

Gates said a plan for phase III trials for the vaccine would likely be announced later this year. But he called on governments and other philanthropists to step up to help fund the trials, as well as other TB innovations.

He estimated that the vaccine trial would cost $700-800m to "prove it out".

"So even though we'll be a big funder of that, we also need partners to come in and do that with us," he said, adding that vaccine development has a high risk of failure so needs real commitment from funders.

TB, a bacterial disease that mostly affects the lungs, is preventable and treatable, but 10 million people still catch it annually, and 1.6 million people died from TB in 2021, almost entirely in low and middle-income countries. It has long been the world's deadliest infectious disease, although it was briefly overtaken by COVID-19.

Tools to fight TB, like the Bacillus Calmette-Guerin (BCG) vaccine, are imperfect, but there is "hopeful" innovation in vaccines like M72, simpler treatment regimens, and easier to deploy diagnostic tests, said Gates.

There is also a United Nations high level meeting on TB due in September, but Gates said he feared it may not happen due to other global priorities.

"Even if they do it, it won’t get much visibility," he said. "It’s always challenging when there's so many budget priorities. But the world has made a huge mistake not investing more in TB."