TB vaccine could save tens of thousands of SA lives — but only from 2030

In 2019, the World Health Organization (WHO) hailed the results of a candidate tuberculosis (TB) vaccine as a major scientific breakthrough. But years later we are not much closer to seeing the vaccine. Why do TB vaccines take so long to develop compared to Covid vaccines?

Trials of the vaccine, developed by GlaxoSmithKline and named M72/AS01E (M72), among more than 3,500 people suggested that two doses reduced the development of pulmonary TB disease by half.

In South Africa alone, such a vaccine would save tens of thousands of lives each year, and save billions of rands in direct and indirect costs from the disease. Between 2016 and 2018, it was our leading natural cause of death — an average of 29,000 deaths over those years according to Statistics South Africa, though the WHO’s estimates are double that number.

Globally, in 2020, the WHO estimated that 1.5-million people died from TB and nearly six million people fell ill with the disease or had a relapse.

Effective Covid vaccines were developed, tested, and used within a year of the disease’s appearance.

So why are we still waiting for M72’s next step?

A further large trial is needed to confirm the safety and efficacy of the M72 vaccine so that it can be approved by regulatory authorities. But this trial has not yet begun.

The TB trial process take much longer than for Covid in part because TB is a slower moving disease. TB takes years for an infection to turn into the deadly disease that affects the lungs of the patient.

This factor alone would justify the slowness if TB only emerged in recent years — but this disease has been around for thousands of years. The biggest impediment to faster progress is that investment in TB research is puny compared to the need.

It’s taking a long time to bring M72 to patients. Research on the vaccine started in the 1990s. The first small clinical trials, held from 2008 and results published in 2013, found that the vaccine was safe and seemed to work well. Further small trials in Cape Town, Switzerland and India pointed the way to further trials.

Then in 2014-5 over 3,500 participants across Kenya, South Africa and Zambia, took part in a new trial. Results published in 2018, found that the vaccine has 54% protection against active pulmonary TB disease.

But TB vaccine results are a waiting game — enough time has to pass for the researchers to be assured that the vaccine offers lasting protection.

This arrived with the final analysis published in 2019, which looked at how the vaccine performed three years after it was administered.

In the group that received the vaccine, there were 11 cases in South Africa, two in Kenya, and none in Zambia. In those that received the placebo, there were 24 cases in South Africa, one in Kenya and one in Zambia.

This was the first candidate vaccine to show protection against TB disease in a population that was sensitised to TB.

M72 meets the criteria set up by the WHO, which include:

• More than 50% efficacy in preventing pulmonary TB;


• Ten years or more of protection after immunisation;


• Safe — particularly for higher risk groups like people living with HIV;


• As few booster shots as possible (no more than two);


• Non-interference with other vaccines;


• A way of testing that a person is protected by the vaccine (like sero-prevalence testing);


• Cost-effective or easy to produce.

How M72 works