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Over 100 yrs of BCG: Why is Tuberculosis still here?
A century after BCG, the challenge is not that vaccination has made no difference. It is that the protection we have is not yet enough. Progress will depend on understanding why, testing new approaches and investing in the science needed to turn promising ideas into effective interventions, writes Dr Ludoviko Zirimenya
Dr Ludoviko Zirimenya. (File)
By: Admin ., Journalist @New Vision
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OPINION
By Dr Ludoviko Zirimenya
According to the World Health Organisation, an estimated 10.7 million people developed Tuberculosis (TB) worldwide, and 1.23 million died from the disease in 2024.
As a doctor who previously worked in palliative care, I saw the consequences of TB beyond clinical diagnosis. I cared for patients experiencing advanced disease, including people living with HIV and witnessed how serious illness could affect not only patients’ health, but also their families and livelihoods. Those experiences shaped my interest in finding better ways to prevent infectious diseases.
The Bacille Calmette-Guérin (BCG) vaccine, which is routinely given at birth in Uganda, provides important protection against severe forms of TB in young children. However, its effectiveness against pulmonary TB in adolescents and adults, the form responsible for most TB transmission, is limited. This is why researchers around the world are working to develop improved vaccines that can provide stronger and longer-lasting protection.
A vaccine that offers stronger protection against disease in these populations could make an important contribution to reducing illness and transmission.
Complexities of better TB vaccine development
Part of the challenge lies in the disease’s complexity. Many people carry the bacteria without developing active TB, while others become ill, sometimes years after infection. Scientists still do not fully understand which immune responses reliably protect against the disease.
Researchers are exploring whether the mode of vaccine delivery affects protection. Since TB is usually acquired by inhaling bacteria and primarily affects the lungs, delivering vaccines directly to the respiratory tract might stimulate immune responses where infection begins.
However, this approach remains under investigation; delivery to the lungs does not guarantee better protection. Through international collaboration, we are working to answer these questions.
A vaccine that offers stronger protection against disease in these populations could make an important contribution to reducing illness and transmission.
Complexities of better TB vaccine development
Part of the challenge lies in the disease’s complexity. Many people carry the bacteria without developing active TB, while others become ill, sometimes years after infection. Scientists still do not fully understand which immune responses reliably protect against the disease.
Researchers are exploring whether the mode of vaccine delivery affects protection. Since TB is usually acquired by inhaling bacteria and primarily affects the lungs, delivering vaccines directly to the respiratory tract might stimulate immune responses where infection begins.
However, this approach remains under investigation; delivery to the lungs does not guarantee better protection. Through international collaboration, we are working to answer these questions.
At the MRC/UVRI and LSHTM Uganda Research Unit, we are part of the T5-TBVAC consortium, bringing together researchers in Uganda, Senegal, the United Kingdom and partner institutions to investigate new approaches to TB vaccination.
The research includes the evaluation of ChAdOx1 T5, an experimental vaccine candidate being studied as a booster for people who have previously received BCG. Researchers will assess its safety and immune responses following delivery by inhalation or injection in clinical trials. The findings will help us understand whether this approach warrants further development and whether it could contribute to the search for more effective TB vaccines.
For countries such as Uganda, participation in this research is particularly important. TB continues to impose a substantial burden on communities, and African populations must be represented in the studies that determine the future of prevention. Research conducted in different settings will help scientists understand how vaccine candidates perform across populations and build local expertise in clinical trials, immunology and vaccine development. It will also ensure that African researchers and institutions contribute to answering questions that matter to the health of their own communities.
Better vaccines alone will not end TB. Early diagnosis, effective treatment, preventive therapy for eligible people, improved living conditions and strong health services will remain essential. But a vaccine that offers meaningful protection against TB in adolescents and adults could become an important additional tool in reducing its toll.
A century after BCG, the challenge, therefore, is not that vaccination has made no difference. It is that the protection we have is not yet enough. Progress will depend on understanding why, testing new approaches and investing in the science needed to turn promising ideas into effective interventions. That is the work researchers are undertaking today and why it deserves sustained scientific attention and public investment.
The writer is a researcher at the Medical Research Council/ Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI&LSHTM)
The research includes the evaluation of ChAdOx1 T5, an experimental vaccine candidate being studied as a booster for people who have previously received BCG. Researchers will assess its safety and immune responses following delivery by inhalation or injection in clinical trials. The findings will help us understand whether this approach warrants further development and whether it could contribute to the search for more effective TB vaccines.
For countries such as Uganda, participation in this research is particularly important. TB continues to impose a substantial burden on communities, and African populations must be represented in the studies that determine the future of prevention. Research conducted in different settings will help scientists understand how vaccine candidates perform across populations and build local expertise in clinical trials, immunology and vaccine development. It will also ensure that African researchers and institutions contribute to answering questions that matter to the health of their own communities.
Better vaccines alone will not end TB. Early diagnosis, effective treatment, preventive therapy for eligible people, improved living conditions and strong health services will remain essential. But a vaccine that offers meaningful protection against TB in adolescents and adults could become an important additional tool in reducing its toll.
A century after BCG, the challenge, therefore, is not that vaccination has made no difference. It is that the protection we have is not yet enough. Progress will depend on understanding why, testing new approaches and investing in the science needed to turn promising ideas into effective interventions. That is the work researchers are undertaking today and why it deserves sustained scientific attention and public investment.
The writer is a researcher at the Medical Research Council/ Uganda Virus Research Institute and London School of Hygiene and Tropical Medicine (MRC/UVRI&LSHTM)