African researchers push for human challenge trial to fight TB
Researchers and nonprofit supporters in Malawi have launched an effort to begin human challenge trials for TB, to accelerate the development of a promising TB vaccine.
While TB is easily treated in high-income countries, the disease kills globally – more than 1.6 million people died of TB in 2021 and drug-resistant cases are on the rise. An effective and long-lasting vaccine could save millions of lives in places where proper treatment cannot be obtained.
The push to accelerate vaccine development comes from the Malawi-Liverpool Wellcome Trust’s Clinical Research Program (MLW), Vox’s Kelsey Piper reported, and it still faces considerable headwinds, including numerous ethical reviews and d other levels of institutional approval.
While TB is easily treated in high-income countries, the disease kills globally – more than 1.6 million people died of TB in 2021 and drug-resistant cases are on the rise.
A challenge to save lives: A human challenge trial (HCT) is a type of clinical trial in which volunteers are deliberately infected – “challenge” – with a pathogen.
The idea is that rather than spending huge sums of money, recruiting tens of thousands of people, and waiting years for infections to occur naturally, like in a traditional phase 3 trial, you could immediately see if your new TB vaccine works, with only dozens or hundreds of volunteers.
HCTs have the potential to cut months or years off the search for vaccines and drugs, which could mean thousands of lives saved. They also carry an inherent risk, as infected volunteers are at risk of serious illness or even death.
The key is to balance these two competing concerns through well-designed assays: using the minimum amount of pathogen needed; only accept young and healthy volunteers; and having medical interventions ready to cure patients who fall ill.
Most important, however, is that volunteers understand the risks and benefits and give informed consent.
Knock down TB: For researchers and advocacy nonprofit HCT 1Day Sooner, this approach could be a particularly powerful tool for developing a better TB vaccine.
It’s a position that has been backed by experts in biotechnology and the University of Oxford, Vox’s Piper reported. The Oxford researchers actually have experience managing multiple HCTs for diseases like malaria and COVID-19.
Although relegated to Victorian fiction in the developed world, the disease burden of tuberculosis is high. According to the WHO, 1.6 million people died of tuberculosis in 2021, making it the second deadliest infectious disease in the world, behind COVID-19 – despite the existence of treatments and a vaccine against tuberculosis available.
According to WHO, a handful of countries in Asia and Africa have a particularly high TB burden: 87% of all cases occurred in Bangladesh, China, DRC, India, Indonesia, Nigeria, the Philippines and Pakistan.
Although there is a widely administered tuberculosis vaccine, it is only about 60% effective in preventing active infections, Piper noted, and although antibiotics do work, there are strains of bacteria that develop drug resistance.
The bottom line: With millions still dying from the disease, there is enormous potential to improve our defenses, and researchers and advocates say the speed and cost-effective benefits of HCTs make it a prime candidate to do so.
“Alternatives to a human challenge trial are very, very expensive,” 1DaySooner President Josh Morrison told Piper.
Because TB is primarily a threat in developing countries, the incentive for US and European pharmaceutical companies to conduct large-scale trials for promising new TB vaccine candidates is weak. It will therefore be largely up to non-profit organizations and developing countries themselves to take this issue forward.
According to 1Day Africa Director Zacharia Kafuko, community volunteers are genuinely ready and willing to be infected with TB to protect others – a view that has been reinforced by a study MLW carried out on participants in the sequel to a previous HCT.
“They’re actually wondering why it’s taking so long, why it has to be approved by researchers in the UK,” Kafuko told Piper. “They believe that this research should be pioneering in Africa. The people who should benefit from vaccines are here.
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