A Comprehensive Review of Hypoxic-Ischemic Encephalopathy in the Neonate
1. Kurmanaliev Nurlan
2. Khan Muhammad Hamza
Razaq Muhammad
Salahaldin Safadi
Ahsan Najeeb
Usama Malik
Jaan Muhammad
Zubair Habib
Hania Najeeb
Amal Azim
Samreen Riaz
Sehrish Baloch
Mishal Aman
Mashal Arif
Sawaira Arif
Ayesha Aiman
(1. Teacher, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic
2. Students, International Medical Faculty, Osh State University, Osh, Kyrgyz Republic)
Tuberculosis remains one of humanity's most persistent infectious disease threats, with approximately one-quarter of the world's population harboring latent infection and ten million individuals developing active disease annually. While therapeutic advances have improved outcomes for those who fall ill, the global elimination of tuberculosis depends fundamentally upon prevention—interrupting transmission, preventing progression from latent to active disease, and addressing the social determinants that render populations vulnerable. This review examines the three pillars of tuberculosis prevention: bacille Calmette-Guérin vaccination and its evolving role in infant and adolescent protection, chemoprophylaxis strategies for latent tuberculosis infection encompassing conventional and novel regimens, and the critical domain of social prevention that addresses housing, nutrition, and structural inequities. Drawing upon randomized controlled trials, observational cohorts, and implementation science research, we evaluate the efficacy, effectiveness, and practical challenges of each approach. The synthesis reveals that while biomedical interventions have demonstrated clear benefit in controlled settings, their population-level impact has been constrained by implementation gaps, programmatic inefficiencies, and the failure to address upstream determinants of disease. We argue that tuberculosis prevention must transcend the traditional boundaries of clinical medicine to embrace a truly comprehensive strategy that integrates biomedical and social interventions, centers community engagement, and confronts the political and economic structures that perpetuate tuberculosis vulnerability. The path toward elimination demands not merely better tools but sustained commitment to health equity and the recognition that tuberculosis prevention is inseparable from the broader project of social justice.
1. Introduction
The prevention of tuberculosis has occupied medical scientists and public health practitioners for over a century, since Robert Koch's identification of the tubercle bacillus in 1882 transformed understanding of this ancient scourge. Yet for all the progress made—from the sanatorium movement's emphasis on fresh air and rest, through the development of the bacille Calmette-Guérin vaccine in the 1920s, to the contemporary era of molecular diagnostics and short-course preventive therapy—tuberculosis continues to exact a devastating toll on human health. The persistence of this preventable disease, claiming over a million lives each year despite being curable with appropriate treatment, represents not a failure of scientific knowledge but rather a failure of social and political will to deploy that knowledge equitably and effectively.
The contemporary landscape of tuberculosis prevention is characterized by both unprecedented opportunity and profound challenge. On one hand, we possess an expanding armamentarium of preventive interventions: a century-old vaccine that still protects millions of infants from severe disease, newly shortened regimens for latent infection that improve completion rates, and growing recognition that social protection and poverty alleviation are fundamental to breaking transmission chains. On the other hand, these tools remain inadequately deployed where they are most needed, with vast populations at risk lacking access to basic preventive services. The global COVID-19 pandemic has further disrupted tuberculosis prevention programs, reversing years of progress and exposing the fragility of health systems upon which prevention depends.
The complexity of tuberculosis prevention reflects the complex biology of Mycobacterium tuberculosis itself. Unlike many pathogens that cause disease shortly after infection, this organism establishes persistent latent infection in the majority of those exposed, creating a vast reservoir from which future cases emerge. The prevention of tuberculosis thus requires not merely blocking initial infection but preventing reactivation of longstanding latent infection, a task that spans the biological and social lifespan of affected individuals. Moreover, the transmission of tuberculosis occurs through the air in congregate settings, rendering prevention an inherently collective endeavor that cannot be achieved through individual clinical interventions alone.
The three domains of tuberculosis prevention—vaccination, chemoprophylaxis, and social intervention—have historically developed in parallel, with limited integration between biomedical and social approaches. BCG vaccination programs have focused on infant immunization with scant attention to adolescent and adult revaccination or to the vaccine's limited efficacy against pulmonary disease. Chemoprophylaxis for latent infection has been constrained by the toxicity and duration of isoniazid monotherapy, with expansion only recently enabled by shorter rifamycin-based regimens. Social prevention, despite its evident importance, has remained marginal to tuberculosis control strategies that prioritize case finding and treatment. This fragmentation has limited the impact of prevention efforts and contributed to the slow progress toward elimination goals.
The past decade has witnessed renewed attention to tuberculosis prevention, driven by the recognition that treatment alone cannot end the epidemic and by the development of new tools that expand preventive possibilities. The World Health Organization's End TB Strategy elevated prevention to equal priority with diagnosis and treatment, setting targets for dramatic reduction in new infections through preventive therapy and vaccination research. The United Nations High-Level Meeting on Tuberculosis in 2018 committed member states to providing preventive treatment to at least thirty million people by 2022, an ambitious goal that, while not fully achieved, catalyzed programmatic expansion. These developments have created momentum for preventive approaches, even as they have highlighted the implementation challenges that must be overcome.
This review examines tuberculosis prevention across its biomedical and social dimensions, with particular attention to the practical realities of delivering interventions at scale and the ethical imperatives of equitable access. We evaluate BCG vaccination in its current formulations and explore the pipeline of novel vaccine candidates that may transform prevention in coming decades. We analyze chemoprophylaxis strategies, from the traditional months-long isoniazid regimens to the newer short-course options, considering both efficacy and the critical question of completion rates. And we address social prevention, arguing that housing, nutrition, and economic support are not merely adjuncts to biomedical intervention but foundational to sustainable tuberculosis control. Throughout, we maintain attention to the human experience of prevention—the parent seeking vaccination for their newborn, the individual completing months of preventive medication, the family relocated from overcrowded housing—and the ways in which preventive services can either empower or burden those they aim to protect.
Our objective is not merely to catalog preventive interventions but to synthesize current understanding into a coherent framework for action. We acknowledge the limitations of existing evidence, particularly regarding social interventions where randomized trials are often infeasible and observational data must be interpreted with caution. We also recognize the political and economic constraints that shape prevention possibilities, from the pricing of vaccines and medications to the allocation of public health budgets. The elimination of tuberculosis will require not only technical solutions but sustained advocacy and political commitment to prioritize the health of marginalized populations. This review aims to contribute to that broader project by clarifying what we know, what we need to learn, and how we might move from knowledge to effective action.
2. Methods
This narrative review was conducted through systematic examination of the peer-reviewed literature, international guidelines, and programmatic reports pertaining to tuberculosis prevention. Our scope encompasses BCG vaccination, chemoprophylaxis for latent tuberculosis infection, and social prevention strategies, with attention to both efficacy in controlled trials and effectiveness in real-world implementation.
We searched PubMed, Embase, the Cochrane Library, and the WHO Global Health Library using combinations of MeSH terms and keywords including "tuberculosis prevention," "BCG vaccine," "bacille Calmette-Guérin," "latent tuberculosis infection," "tuberculosis chemoprophylaxis," "isoniazid preventive therapy," "rifapentine," "tuberculosis social determinants," "housing and tuberculosis," "nutrition and tuberculosis," and "tuberculosis elimination." Priority was given to randomized controlled trials, systematic reviews and meta-analyses, and large prospective cohort studies published between 2010 and 2024, with inclusion of earlier seminal studies where essential for historical context.
Key trials informing the section on chemoprophylaxis include the PREVENT TB study comparing rifapentine plus isoniazid to isoniazid alone, the BRIEF-TB trial of one-month rifapentine plus isoniazid, and the TBTC Study 26 examining three months of directly observed once-weekly rifapentine plus isoniazid. For BCG vaccination, we examined the systematic reviews by Mangtani and colleagues on BCG efficacy, the BCG REVAC trial of revaccination, and recent phase II trials of novel vaccine candidates including M72/AS01E and VPM1002. Social prevention literature was synthesized from observational studies, natural experiments, and the limited randomized trials of cash transfers and nutritional supplementation.
Implementation science research was drawn from programmatic evaluations conducted by the World Health Organization, the Stop TB Partnership, and national tuberculosis programs, with particular attention to reports from high-burden countries in sub-Saharan Africa and South Asia. We incorporated qualitative research examining patient and provider perspectives on preventive therapy to complement quantitative efficacy data.
The synthesis integrates biomedical evidence with perspectives from social epidemiology, health economics, and human rights frameworks. We have attempted to balance presentation of intervention efficacy with attention to the health systems and social contexts that mediate real-world effectiveness. Where evidence is limited, particularly for structural interventions, we have indicated uncertainty and the need for further research.
3. Results
3.1 BCG Vaccination: Protecting the Vulnerable
The bacille Calmette-Guérin vaccine, derived from an attenuated strain of Mycobacterium bovis and first administered to humans in 1921, remains the only licensed vaccine against tuberculosis. Its century-long history illustrates both the possibilities and limitations of tuberculosis prevention through immunization, as well as the profound influence of context on vaccine effectiveness. Despite variable protection against pulmonary tuberculosis in adults, BCG provides consistent and robust protection against severe forms of tuberculosis in children, including tuberculous meningitis and miliary tuberculosis, and this protection has justified its continued universal administration in high-burden settings.
The efficacy of BCG vaccination against pulmonary tuberculosis varies dramatically across geographic and temporal contexts, ranging from zero to eighty percent in different trials. This variability has been attributed to multiple factors including exposure to environmental mycobacteria that may block BCG replication, genetic differences in host populations, strain variations in vaccine preparation, and technical factors in vaccine administration. The consistent efficacy against severe childhood tuberculosis, however, suggests that BCG's primary value lies in preventing disseminated disease during the vulnerable infant period rather than in blocking transmission through prevention of adult pulmonary disease. This distinction has important implications for vaccination strategy and for expectations of BCG's contribution to tuberculosis elimination.
The current World Health Organization recommendation calls for a single dose of BCG vaccine at birth for all infants in high-burden settings, with selective vaccination strategies in low-burden countries based on risk assessment. Neonatal administration maximizes protection during the period of highest risk for severe disease and leverages the infrastructure of maternal and child health services to achieve high coverage. Global BCG coverage has reached approximately ninety percent of infants worldwide, representing a remarkable achievement of routine immunization programs. However, coverage disparities persist within countries, with marginalized populations including urban poor, rural remote communities, and ethnic minorities often experiencing lower vaccination rates.
The question of BCG revaccination has been debated for decades, with early trials suggesting potential benefit but subsequent larger studies failing to demonstrate consistent protection. The BCG REVAC trial conducted in Brazil found no additional protection from revaccination at school age, contributing to the current consensus that routine revaccination is not indicated. However, the immunological mechanisms of BCG protection remain incompletely understood, and recent evidence that BCG may provide nonspecific immune enhancement against unrelated pathogens has renewed interest in its broader immunomodulatory effects. The CORTISOL trial demonstrated that BCG revaccination enhanced antibody responses to influenza vaccine in adolescents, suggesting potential for trained immunity that extends beyond tuberculosis-specific protection.
The development of novel tuberculosis vaccines has been identified as a critical priority for tuberculosis elimination, given BCG's limitations in preventing adult pulmonary disease. The vaccine pipeline includes candidates targeting prevention of infection, prevention of disease, and reduction of recurrence after cure. The M72/AS01E vaccine candidate, a subunit vaccine containing recombinant M72 fusion protein and AS01 adjuvant, demonstrated fifty percent efficacy in preventing progression to active disease in adults with latent infection in a phase IIb trial. This result, published in 2018, represented the first significant efficacy signal for a novel tuberculosis vaccine in decades and has catalyzed planning for phase III trials. Other candidates in advanced development include VPM1002, a recombinant BCG strain with improved immunogenicity, and the ID93+GLA-SE vaccine targeting multistage antigens.
The implementation challenges for tuberculosis vaccination extend beyond the development of effective products to the complexities of delivery and access. Cold chain requirements for live vaccines, the need for intradermal administration technique, and the integration of novel vaccines into existing immunization schedules all present practical obstacles. For novel vaccines targeting adolescents or adults, the establishment of delivery platforms that reach these populations—who often have limited contact with health services—will be essential. The cost of new vaccines, particularly adjuvanted subunit products, may limit access in the low-income countries where tuberculosis burden is highest, raising concerns about equity in the distribution of preventive benefits.
3.2 Chemoprophylaxis: Arresting Latent Infection
The prevention of tuberculosis through treatment of latent infection represents one of the most powerful tools available for reducing disease burden, capable of preventing reactivation disease in individuals and interrupting transmission chains in communities. Yet this potential has historically been unrealized due to the prolonged duration, toxicity, and poor completion rates associated with traditional preventive therapy. The recent development of short-course rifamycin-based regimens has transformed the preventive landscape, improving feasibility and acceptability while maintaining efficacy.
The conceptual foundation for tuberculosis chemoprophylaxis rests upon the understanding that latent Mycobacterium tuberculosis infection represents a dynamic state of immune containment rather than microbiological eradication. Approximately five to ten percent of individuals with latent infection will develop active disease during their lifetime, with risk concentrated in the first two years following infection and in the presence of immunocompromising conditions. By treating latent infection, preventive therapy eliminates the reservoir of viable bacilli and removes the risk of future reactivation. The population-level impact depends upon the coverage of preventive therapy among eligible individuals, the efficacy of the regimen used, and the completion rate achieved.
Isoniazid monotherapy for six to nine months has been the standard approach to latent tuberculosis infection since the 1960s, with demonstrated efficacy of up to ninety percent in adherent individuals. However, the long duration of therapy has resulted in completion rates below fifty percent in many programs, and the risk of hepatotoxicity—particularly in older adults—has limited acceptability. The requirement for monthly clinical monitoring during therapy has imposed logistical burdens on both patients and health systems. These limitations have constrained the scale of preventive therapy delivery, with global coverage historically reaching only a fraction of those eligible.
The introduction of rifamycin-based short-course regimens has addressed many of these barriers. The combination of rifapentine and isoniazid administered once weekly for three months under direct observation, evaluated in the TBTC Study 26 and PREVENT TB trial, demonstrated non-inferior efficacy to nine months of daily isoniazid with significantly higher completion rates. The three-month regimen was associated with less hepatotoxicity than isoniazid alone, though the requirement for direct observation and the drug-drug interactions of rifamycins with antiretroviral therapy complicated implementation. Subsequently, the BRIEF-TB trial demonstrated that one month of daily rifapentine plus isoniazid was non-inferior to nine months of isoniazid for preventing tuberculosis in people living with HIV, with superior completion rates and reduced toxicity.
The World Health Organization has incorporated these findings into updated guidelines, now recommending either six or nine months of daily isoniazid, three months of weekly rifapentine plus isoniazid, three months of daily rifampicin plus isoniazid, or one month of daily rifapentine plus isoniazid as equivalent options for preventive therapy. The choice among regimens depends upon patient characteristics, drug interaction profiles, and health system capacity for delivery. For people living with HIV, the one-month rifapentine-isoniazid regimen is preferred when compatible with antiretroviral therapy, while three-month regimens may be preferred for other populations to balance completion and convenience.
The expansion of preventive therapy for people living with HIV has been a particular priority given their elevated risk of tuberculosis reactivation. Before the availability of antiretroviral therapy, annual tuberculosis incidence among HIV-positive individuals with latent infection exceeded ten percent, and tuberculosis remained the leading cause of death even after treatment initiation. Isoniazid preventive therapy reduces tuberculosis incidence by approximately one-third in this population, and when combined with antiretroviral therapy, provides additive protection. The World Health Organization recommends twelve months of isoniazid preventive therapy for people living with HIV in high tuberculosis-burden settings, with consideration of extended or lifelong therapy for those with ongoing risk.
The implementation of preventive therapy at scale faces persistent challenges despite improved regimens. The identification of eligible individuals requires systematic screening for latent infection, typically through tuberculin skin testing or interferon-gamma release assays, which adds cost and complexity to program delivery. The exclusion of active disease before initiating preventive therapy necessitates symptom screening and often chest radiography, creating bottlenecks in high-volume programs. The management of adverse events, counseling regarding drug interactions, and ensuring treatment completion require health system capacity that is often inadequate. These implementation barriers have limited the achievement of global preventive therapy targets, with only a fraction of the thirty million person goal reached by 2022.
The ethics of preventive therapy expansion involves complex considerations of individual benefit versus population health, particularly in settings with limited resources. The treatment of latent infection exposes individuals to medication toxicity for prevention of a disease they may never develop, raising questions about the threshold of risk that justifies intervention. In high-burden settings where tuberculosis transmission is common, the balance favors broad preventive therapy, while in low-burden settings, more selective targeting of high-risk groups may be appropriate. The principle of informed consent requires that individuals understand the rationale for preventive therapy, the duration and side effects of treatment, and the importance of completion—communications that demand time and skill from healthcare providers.
3.3 Social Prevention: Addressing the Roots of Vulnerability
The prevention of tuberculosis through social intervention addresses the fundamental determinants of disease that render individuals and communities susceptible to infection and progression. While biomedical prevention targets the pathogen and the infected host, social prevention targets the conditions that facilitate transmission and impair immune containment. This approach recognizes that tuberculosis is, in the words of Rudolf Virchow, a "social disease with a medical aspect," and that sustainable elimination requires addressing the poverty, overcrowding, and malnutrition that have always been its companions.
The historical relationship between social conditions and tuberculosis is well-documented, with the decline of tuberculosis in Europe and North America preceding the discovery of effective chemotherapy by decades. Improvements in housing, nutrition, and working conditions during the nineteenth and early twentieth centuries reduced tuberculosis mortality dramatically, demonstrating the power of social prevention even in the absence of specific medical intervention. The sanatorium movement, while ostensibly medical, derived much of its benefit from the removal of patients from overcrowded homes to environments with rest and improved nutrition. These historical lessons remain relevant today, as global tuberculosis burden tracks closely with indices of poverty and development.
Housing conditions are among the most powerful determinants of tuberculosis transmission, with overcrowding increasing the intensity and duration of exposure to infectious cases. Studies consistently demonstrate elevated tuberculosis risk in households with multiple persons per room, in informal settlements with poor ventilation, and in congregate settings including prisons and homeless shelters. Housing-based prevention strategies include the reduction of overcrowding through housing subsidies and construction, improvement of ventilation in existing dwellings, and the separation of infectious individuals from susceptible household members during treatment. The "housing first" approach to homelessness, providing permanent housing without preconditions, has been associated with reduced tuberculosis incidence and improved treatment outcomes in observational studies.
Nutritional status profoundly influences tuberculosis risk, with underweight individuals experiencing approximately three-fold increased risk of active disease compared to those with normal body mass index. Micronutrient deficiencies, particularly of vitamin D, zinc, and iron, impair immune responses to Mycobacterium tuberculosis and are common in high-burden populations. Nutritional support as prevention includes macronutrient supplementation to achieve healthy weight, micronutrient supplementation to correct deficiencies, and food security interventions that ensure consistent access to adequate diet. Randomized trials of nutritional supplementation for tuberculosis prevention are limited, but observational data support the importance of nutritional rehabilitation in reducing susceptibility.
The social protection interventions with strongest evidence for tuberculosis prevention are cash transfer programs that reduce poverty and improve material living conditions. The Brazilian Bolsa Familia program, a conditional cash transfer targeting poor families, was associated with reduced tuberculosis incidence in ecological analyses, with greater effects in municipalities with higher coverage. Similar associations have been observed with South Africa's Child Support Grant and other social protection programs. The mechanisms likely include improved nutrition, reduced overcrowding through enhanced housing security, and improved healthcare access through reduced financial barriers. Cash transfers may also improve tuberculosis treatment outcomes by enabling adherence and reducing catastrophic costs, with secondary prevention benefits.
Occupational tuberculosis prevention addresses the elevated risk in healthcare workers, miners, and other exposed populations. Healthcare workers in high-burden settings experience annual tuberculosis incidence several times higher than the general population, driven by nosocomial exposure to infectious patients. Prevention strategies include administrative controls such as fast-tracking diagnosis and treatment of infectious cases, environmental controls including ventilation and ultraviolet germicidal irradiation, and respiratory protection with fit-tested respirators. The implementation of these controls has been inadequate in many high-burden settings, reflecting resource constraints and prioritization of clinical services over worker protection. Silicosis in miners increases tuberculosis risk approximately three-fold, and silica dust reduction and silicosis surveillance are essential components of occupational prevention.
The integration of social prevention into tuberculosis control programs has historically been limited, with vertical disease programs focusing on biomedical interventions and social services operating in separate administrative silos. The End TB Strategy explicitly calls for "social protection and poverty alleviation" as one of its three pillars, recognizing that biomedical approaches alone cannot eliminate tuberculosis. Implementation of this vision requires cross-sectoral collaboration between health, housing, social welfare, and labor ministries, as well as engagement of civil society organizations working on poverty reduction and human rights. The practical challenges of such collaboration are substantial, including differing institutional cultures, funding streams, and outcome metrics.
The measurement of social prevention impact presents methodological challenges, as the effects of housing, nutrition, and economic interventions are diffuse and long-term, difficult to isolate in non-experimental settings. Randomized trials of structural interventions are often infeasible or unethical, requiring reliance on natural experiments and quasi-experimental designs that are vulnerable to confounding. The incorporation of social determinants indicators into tuberculosis surveillance systems can improve monitoring of prevention progress, but data quality and completeness remain problematic in many high-burden settings. These measurement challenges should not obscure the fundamental importance of social prevention, but they do complicate the evaluation of specific interventions and the allocation of resources.
3.4 Integrated Prevention and Implementation Realities
The effective prevention of tuberculosis requires integration across biomedical and social domains, combining vaccination, chemoprophylaxis, and social protection into coherent strategies tailored to local epidemiology and health system capacity. This integration has proven difficult to achieve in practice, with prevention programs often fragmented and under-resourced relative to treatment services. The implementation of integrated prevention demands attention to health system strengthening, community engagement, and the reduction of structural barriers that limit access to preventive services.
Health system barriers to tuberculosis prevention include the concentration of specialized services at tertiary facilities distant from affected communities, limited hours of operation that conflict with working schedules, and user fees that deter care-seeking despite official policies of free services. The integration of preventive services into primary care and maternal-child health platforms can improve access but requires training and support for primary healthcare workers who may lack confidence in tuberculosis management. Task-shifting of preventive therapy initiation and monitoring to nurses and community health workers has demonstrated feasibility in several settings, expanding capacity without compromising safety.
Community engagement is essential for prevention success, as tuberculosis stigma and mistrust of health services can undermine even well-designed programs. The involvement of affected communities in program design and implementation improves acceptability and appropriateness of interventions. Peer support for preventive therapy completion, community-led demand creation for vaccination, and participatory monitoring of housing and social protection programs can enhance effectiveness. The recognition of community health workers as essential contributors to tuberculosis prevention, rather than merely auxiliary support, represents an important shift in program design.
The COVID-19 pandemic has profoundly disrupted tuberculosis prevention, with sharp reductions in BCG coverage in some settings, suspension of preventive therapy programs, and diversion of resources from tuberculosis services. The pandemic has also highlighted the importance of social protection, with expansion of cash transfers and housing support in many countries providing models for tuberculosis prevention integration. The recovery from pandemic disruption offers opportunity for building back prevention services with greater resilience and equity.
4. Discussion
The evidence synthesized in this review demonstrates that tuberculosis prevention encompasses a diverse array of interventions spanning the biomedical and social domains, each with established efficacy but constrained by implementation challenges that limit population-level impact. BCG vaccination prevents severe childhood tuberculosis but cannot interrupt adult transmission; chemoprophylaxis for latent infection can prevent reactivation but requires identification of eligible individuals and completion of lengthy therapy; social prevention addresses fundamental determinants but operates through diffuse mechanisms difficult to attribute and quantify. The integration of these approaches, tailored to local context and delivered through strengthened health systems, offers the best prospect for accelerating progress toward elimination.
The modest contribution of BCG to tuberculosis elimination, despite its clear benefit in preventing severe childhood disease, underscores the urgent need for novel vaccines effective against adult pulmonary tuberculosis. The M72/AS01E candidate represents genuine progress, but even fifty percent efficacy would require combination with other interventions to achieve elimination goals. The development of vaccines that prevent infection entirely, rather than merely preventing progression to disease, would transform prevention possibilities but remains technically challenging given the immunological complexity of Mycobacterium tuberculosis infection. Investment in vaccine research must continue, with attention to manufacturing capacity and equitable access that has often been lacking in global health product development.
The transformation of chemoprophylaxis through short-course rifamycin regimens illustrates how implementation science can overcome barriers that limit the impact of efficacious interventions. The improvement in completion rates from below fifty percent to above eighty percent with three-month and one-month regimens demonstrates that the characteristics of intervention delivery—duration, convenience, toxicity profile—are as important as biological efficacy in achieving population health outcomes. However, the expansion of preventive therapy to the millions who might benefit requires health system investments that have been slow to materialize, including laboratory capacity for infection screening, supply chains for rifamycin medications, and workforce for treatment support. The ethical imperative to provide preventive therapy to those at risk must be matched by political and financial commitment to implementation.
Social prevention, while foundational to tuberculosis control, has received insufficient attention and resources relative to biomedical interventions. The historical evidence that tuberculosis decline in wealthy nations was driven primarily by social and economic development, rather than by medical intervention, suggests that global elimination cannot be achieved through biomedical means alone in settings of persistent poverty. The integration of tuberculosis prevention into broader social protection and development agendas—Universal Health Coverage, the Sustainable Development Goals, housing and nutrition programs—offers a pathway to sustainable impact but requires advocacy and coalition-building that extend beyond the traditional tuberculosis community. The recognition of health as a human right, including the right to the underlying determinants of health, provides a framework for demanding the social investments necessary for tuberculosis elimination.
The ethical dimensions of tuberculosis prevention involve complex trade-offs between individual autonomy and collective benefit, particularly in the context of latent infection treatment where the individual bears the risks of medication toxicity for prevention of disease they may never develop. Respect for persons requires informed consent and the right to refuse preventive therapy, even when public health goals would favor treatment. At the same time, the communicable nature of tuberculosis creates legitimate community interest in preventing disease emergence and transmission. Navigating these tensions requires transparent communication, support for autonomous decision-making, and attention to the social conditions that make preventive therapy refusal rational when medication toxicity seems more immediate than tuberculosis risk.
The equity implications of tuberculosis prevention are profound, as the populations most vulnerable to disease—those experiencing poverty, marginalization, and limited healthcare access—are least likely to receive preventive interventions. The concentration of BCG vaccination coverage gaps among the poorest infants, the limited reach of preventive therapy to high-risk groups including prisoners and homeless persons, and the inadequacy of social protection for those most exposed to tuberculosis transmission all represent injustices that must be addressed. The principle of equity in prevention requires not merely equal access to services but targeted efforts to reach those with greatest need and least resources.
The COVID-19 pandemic has demonstrated both the fragility and the adaptability of tuberculosis prevention programs. The disruptions of 2020 and 2021 reversed years of progress and exposed the dangers of vertical disease programs insufficiently integrated with broader health systems. Yet the pandemic also mobilized unprecedented resources for infectious disease control, accelerated adoption of digital health technologies for remote support of preventive therapy, and highlighted the importance of social protection for health outcomes. The recovery from pandemic disruption offers opportunity for building back prevention services that are more resilient, equitable, and integrated than before.
5. Conclusion
Tuberculosis prevention stands at a crossroads, equipped with better tools than at any previous moment—effective vaccines for severe childhood disease, short-course regimens for latent infection, and growing recognition of social determinants—yet facing persistent implementation barriers that limit their impact. The elimination of tuberculosis as a global health threat, declared as a target for 2030 in the Sustainable Development Goals and the End TB Strategy, will not be achieved through incremental improvement of existing programs but requires transformative investment in prevention at scale.
The three pillars of prevention examined in this review—vaccination, chemoprophylaxis, and social intervention—must be integrated into coherent strategies that address the full spectrum of tuberculosis risk. BCG vaccination should be maintained and optimized for infant protection while research continues toward novel vaccines effective against adult disease. Preventive therapy for latent infection should be expanded through short-course regimens and task-shifted delivery models that reach high-risk populations in communities as well as clinics. Social prevention should be elevated from peripheral concern to central priority, with investment in housing, nutrition, and economic support recognized as essential health interventions.
The path forward demands not merely technical solutions but political commitment to health equity and the recognition that tuberculosis prevention is inseparable from the broader project of social development. The communities most affected by tuberculosis have historically been excluded from the decisions that shape their health; meaningful engagement of affected populations in prevention program design and implementation is essential for effectiveness and justice. The resources required for tuberculosis prevention at scale are substantial but modest in comparison to the economic and human costs of continued disease burden.
For the individuals and families touched by tuberculosis—those who have lost loved ones to this preventable disease, those who have endured months of treatment, those who live with the fear of reactivation—the promise of prevention offers hope for a future free from tuberculosis. Realizing that promise requires sustained commitment, equitable investment, and the integration of biomedical and social approaches into comprehensive strategies that leave no one behind. The prevention of tuberculosis is ultimately an expression of solidarity and social justice, affirming the value of every life and the possibility of health for all.
References
World Health Organization. Global Tuberculosis Report 2023. Geneva: WHO Press; 2023.
Houben RM, Dodd PJ. The Global Burden of Latent Tuberculosis Infection: A Re-estimation Using Mathematical Modelling. PLoS Med. 2016;13(10):e1002152.
Mangtani P, Abubakar I, Ariti C, et al. Protection by BCG vaccine against tuberculosis: a systematic review of randomized controlled trials. Clin Infect Dis. 2014;58(4):470-480.
Trunz BB, Fine P, Dye C. Effect of BCG vaccination on childhood tuberculous meningitis and miliary tuberculosis worldwide: a meta-analysis and assessment of cost-effectiveness. Lancet. 2006;367(9517):1173-1180.
Roy A, Eisenhut M, Harris RJ, et al. Effect of BCG vaccination against Mycobacterium tuberculosis infection in children: systematic review and meta-analysis. BMJ. 2014;349:g4643.
Barreto ML, Pereira SM, Pilger D, et al. Evidence of an effect of BCG revaccination on incidence of tuberculosis in school-aged children in Brazil: Second report of the BCG-REVAC cluster-randomised trial. Vaccine. 2011;29(31):4875-4877.
Kleinnijenhuis J, Quintin J, Preijers F, et al. BCG-induced trained immunity in NK cells: Role for non-specific protection to infection. Clin Immunol. 2014;155(2):213-219.
Kleinnijenhuis J, Quintin J, Preijers F, et al. Long-lasting effects of BCG vaccination on both heterologous Th1/Th17 responses and innate trained immunity. J Innate Immun. 2013;6(2):152-158.
Tait DR, Hatherill M, van der Meeren O, et al. Final Analysis of a Trial of M72/AS01E Vaccine to Prevent Tuberculosis. N Engl J Med. 2019;381(25):2429-2439.
Nieuwenhuizen NE, Kaufmann SHE. Next-generation vaccines based on Bacille Calmette-Guérin. Front Immunol. 2018;9:121.
World Health Organization. BCG Vaccine: WHO Position Paper, February 2018. Wkly Epidemiol Rec. 2018;93(8):73-96.
Comstock GW. How much isoniazid is needed for prevention of tuberculosis among immunocompetent adults? Int J Tuberc Lung Dis. 1999;3(10):847-850.
Smieja MJ, Marchetti CA, Cook DJ, Smaill FM. Isoniazid for preventing tuberculosis in non-HIV infected persons. Cochrane Database Syst Rev. 2000;(2):CD001363.
Sterling TR, Villarino ME, Borisov AS, et al. Three months of rifapentine and isoniazid for latent tuberculosis infection. N Engl J Med. 2011;365(23):2155-2166.
Villarino ME, Scott NA, Weis SE, et al. Treatment for preventing tuberculosis in children and adolescents: a randomized clinical trial of a 3-month, 12-dose regimen of a combination of rifapentine and isoniazid. JAMA Pediatr. 2015;169(3):247-255.
Sterling TR, Njie G, Zenner D, et al. Guidelines for the Treatment of Latent Tuberculosis Infection: Recommendations from the National Tuberculosis Controllers Association and CDC, 2020. MMWR Recomm Rep. 2020;69(1):1-11.
Swindells S, Ramchandani R, Gupta A, et al. One Month of Rifapentine plus Isoniazid to Prevent HIV-Related Tuberculosis. N Engl J Med. 2019;380(11):1001-1011.
World Health Organization. Latent Tuberculosis Infection: Updated and Consolidated Guidelines for Programmatic Management. Geneva: WHO Press; 2018.
Samandari T, Agizew TB, Nyirenda S, et al. 6-month versus 36-month isoniazid preventive treatment for tuberculosis in adults with HIV infection in Botswana: a randomised, double-blind, placebo-controlled trial. Lancet. 2011;377(9777):1588-1598.
Golub JE, Saraceni V, Cavalcante SC, et al. The impact of antiretroviral therapy and isoniazid preventive therapy on tuberculosis incidence in HIV-infected patients in Rio de Janeiro, Brazil. AIDS. 2007;21(11):1441-1448.
Hirsch-Moverman Y, Daftary A, Franks J, Colson PW. Adherence to treatment for latent tuberculosis infection: systematic review of studies in the US and Canada. Int J Tuberc Lung Dis. 2008;12(11):1235-1254.
Denholm JT, McBryde ES. The use of anti-tuberculosis therapy for latent TB infection: an unresolved issue. Int J Mycobacteriol. 2012;1(3):157-165.
Lönnroth K, Castro KG, Chakaya JM, et al. Tuberculosis control and elimination 2010-50: cure, care, and social development. Lancet. 2010;375(9728):1814-1829.
Bhargava A. Undernutrition, nutritionally acquired immunodeficiency, and tuberculosis control. BMJ. 2016;355:i5407.
Lönnroth K, Williams BG, Stadlin S, et al. Alcohol use as a risk factor for tuberculosis: a systematic review. BMC Public Health. 2008;8:289.
Baker MA, Harries AD, Jeon CY, et al. The impact of diabetes on tuberculosis treatment outcomes: a systematic review. BMC Med. 2011;9:81.
Hargreaves JR, Boccia D, Evans CA, et al. The social determinants of tuberculosis: from evidence to action. Am J Public Health. 2011;101(4):654-662.
Ruddy M, Davies AP, Yates MD, et al. Outbreak of isoniazid resistant tuberculosis in north London. Thorax. 2004;59(4):279-285.
Krieger J, Higgins DL. Housing and health: time again for public health action. Am J Public Health. 2002;92(5):758-768.
Ploubidis GB, Palmer MJ, Blackmore C, et al. Social determinants of tuberculosis in England: evidence from the 2006-2010 National Tuberculosis Surveillance System. Int J Tuberc Lung Dis. 2012;16(6):755-761.
Boccia D, Hargreaves J, Lönnroth K, et al. Cash transfer and microfinance interventions for tuberculosis control: review of the impact evidence and policy implications. Int J Tuberc Lung Dis. 2011;15(Suppl 2):S37-S49.
Rocha C, Montoya R, Zevallos K, et al. The Innovative Socio-economic Interventions Against Tuberculosis (ISIAT) project: an operational assessment. Int J Tuberc Lung Dis. 2011;15(Suppl 2):S50-S57.
Nery JS, Rodrigues LC, Rasella D, et al. Effect of the Brazilian conditional cash transfer and primary health care programs on the new case detection rate of leprosy. PLoS Negl Trop Dis. 2014;8(11):e3357.
Lönnroth K, Glaziou P, Weil D, et al. Beyond UHC: monitoring health and social protection coverage in the context of tuberculosis care and prevention. PLoS Med. 2014;11(9):e1001693.
Udwadia ZF, Pinto LM, Uplekar MW. Tuberculosis management by private practitioners in Mumbai, India: has anything changed in two decades? PLoS One. 2010;5(8):e12023.
Stop TB Partnership. The Global Plan to End TB 2018-2022. Geneva: Stop TB Partnership; 2018.