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Introduction
On Global Tuberculosis (TB) Day, March 24th, We highlight the importance of the BCG vaccine in combating tuberculosis. Developed over 100 years ago, it continues to play a key role in preventing severe forms of TB. This article explores its impact, effectiveness, and the challenges faced.
Mycobacterium tuberculosis (Mtb), the intracellular bacterium that causes TB, remains the leading cause of death among infectious diseases today. In the early 20th century, scientists hoped to control TB through vaccination with the M.bovis BCG vaccine, developed and named after Calmette and Guérin in Lille, France.
The Bacillus Calmette-Guérin (BCG) vaccine is one of the most widely administered vaccines globally. Developed in 1921, it has been instrumental in reducing the burden of TB. While its primary purpose is TB prevention, emerging research suggests broader immunological benefits.
Since 1975, BCG vaccination has been part of the routine newborn immunization schedule in many countries, including Tanzania; in 2023-2024, The Ministry of Health reported that two million doses of the BCG vaccine were administered for protecting newborns against tuberculosis, achieving 95% coverage.
Figure 1. Child receiving BCG vaccine
Effectiveness Against Tuberculosis
Studies show that the BCG vaccine provides 67% protective efficacy in preventing the progression from TB infection to active disease. The vaccine is particularly effective in protecting children from severe forms of TB, such as TB meningitis and miliary TB.
Broader Immunological Benefits
Beyond TB, the BCG vaccine has demonstrated non-specific immune benefits. It enhances the body’s innate immune response, providing protection against various infections, including respiratory diseases. Recent studies suggest a potential role in reducing mortality from neonatal sepsis and even providing some protection against viral infections like COVID-19.
Challenges and Limitations
Despite its benefits, the BCG vaccine has limitations. Its variable efficacy in adults necessitates the development of more effective TB vaccines. The vaccine is also contraindicated in immunocompromised individuals, limiting its use in populations with high HIV prevalence.
Furthermore, Vaccine hesitancy, especially after 2020 with the onset of COVID-19, has become a growing public health challenge. Misinformation, mistrust in health authorities, and concerns about vaccine safety have contributed to skepticism, affecting immunization efforts.
Conclusion
The BCG vaccine plays a vital role in TB prevention, especially in children, while also offering broader immune benefits. However, its limitations in adults and rising vaccine hesitancy pose challenges. Strengthening public trust and advancing TB vaccine research is key to sustaining progress against tuberculosis.
Reference:
- Luca S, Mihaescu T. Maedica-a Journal of Clinical Medicine History of BCG Vaccine. Maedica A Journal of Clinical Medicine. 2013;8(1):53–8.
- Waziri Mkuu wa Jamhuri ya Muungano wa Tanzania Mheshimiwa Kassim Majaliwa (Mb) akipata maelezo kutoka kwa Damaris Richard Mtemi Mama Mzazi wa Mtoto Zungu Japhet Lungwa aliye pandikizwa Uloto (Matibabu ya Sickle Cell) katika Hospitali ya Benjamin Mkapa Jijini Dodoma. 10, Mei 2023 Naibu Waziri Mkuu na Waziri wa Nishati Mheshimiwa Dkt. Doto Mashaka Biteko akizungumza na wazazi waliofika katika zahanati ya Bungoni iliyopo Jijini Dar es Salaam kwa ajili ya kupata huduma za kliniki.
- Effect of BCG vaccination against Mycobacterium tuberculosis infection in children: systematic review and meta-analysis. [cited 2025 Mar 19]; Available from: https://www.bmj.com/
- Sci-Hub | Protection by BCG Vaccine Against Tuberculosis: A Systematic Review of Randomized Controlled Trials. Clinical Infectious Diseases, 58(4), 470–480 | 10.1093/cid/cit790 [Internet]. [cited 2025 Mar 19]. Available from: https://sci-hub.se/https://doi.org/10.1093/cid/cit790
- Gonzalez-Perez M, Sanchez-Tarjuelo R, Shor B, Nistal-Villan E, Ochando J. The BCG Vaccine for COVID-19: First Verdict and Future Directions. Front Immunol [Internet]. 2021 Mar 8 [cited 2025 Mar 19];12:632478. Available from: www.frontiersin.org
Contents by Joel Maduki
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