Contact:
Jillian McKoy, jpmckoy@bu.edu
Michael Saunders, msaunder@bu.edu
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The most comprehensive study to date has found that the duration of protection provided by antibiotics that prevent TB infection from developing into active TB disease differs based on countries’ TB disease prevalence. Officials in high-burden countries should consider providing this treatment with other protective interventions to achieve the global target of eliminating almost all new TB infections and deaths by 2035.
Tuberculosis preventive treatment (TPT) is considered one of the most important public health tools to protect individuals and countries from the deadly infectious disease, and is a critical part of the World Health Organization’s goal to end the global TB epidemic by 2035. This treatment, which includes antibiotic medicines that can prevent inactive TB infections from developing into active disease, has shown to be highly effective, but how long this protection lasts—and whether its duration varies by region or community risk level—remains unclear.
To better understand this duration of protection from TPT, researchers at Boston University School of Public Health (BUSPH) and the University of California, Berkeley School of Public Health (UC Berkeley) estimated TB risk among people with TB infections in 24 countries and found that TPT offered strong initial protection, but long-term protection varied depending on the burden of TB disease in each area.
Published in The Lancet Respiratory Medicine , the study found that TPT offered strong protection during the first 12-24 months across settings with all levels of TB burden. In medium- and low-burden settings, this protection lasted for at least 8 and 13 years, respectively, and there was no significant difference in long-term TB disease risk between people who did and did not complete the full course of medication.
However, in high-burden settings, the initial protection achieved from TPT began waning after just one year of taking the medication.
These findings suggest that expanding TPT among high-risk groups in less-burdened countries can provide meaningful and long-lasting protection against this disease, but high-burden countries should consider combining TPT with other interventions to achieve the long-term benefits these medications are capable of providing.
“In this study, our results corroborated something that was already well-established—TPT is highly effective at preventing TB progression among close contacts and people who have been infected with TB,” says study lead author Ms. Lauren Linde, an epidemiology doctoral student at SPH. “However, our finding that the initial effect of TPT declined so rapidly in very high-burden settings strengthens the case for not placing too much emphasis on TPT in isolation from other interventions that address ongoing community transmission.”
The study presents the most comprehensive data thus far on the duration of protection from a single course of TPT across multiple settings. Nearly two billion people—a quarter of the world’s population—worldwide are infected with TB, the majority of which live in low- and middle-income countries. While most TB infections remain latent and produce no symptoms, about 5-10 percent of infections progress to active TB disease, from which 1.2 million people died in 2024 after developing active TB disease. Preventive treatment consists of one or more antibiotic medications, such as isoniazid and rifapentine, typically prescribed for four months. In 2024, 5.3 million people received this treatment, and officials at the 2023 United Nations High-Level Meeting on Tuberculosis committed to expanding this treatment to 45 million people across the globe, which would cover 90 percent of the global population at highest risk of developing TB. Increasing access to these medications is critical, but understanding the short- and long-term effectiveness of preventive treatment is also essential to achieve the goal of eliminating TB worldwide.
“One of the most encouraging findings is that a single course of preventive treatment was associated with protection lasting well over a decade in settings where TB is relatively uncommon,” says study senior and corresponding author Dr. Leonardo Martinez , assistant professor of epidemiology at UC Berkeley. “Expanding access to preventive treatment in these settings could protect more people from developing TB for many years.”
For the study, Ms. Linde and colleagues utilized data from 44 cohort studies that traced close contacts to individuals with TB in 24 countries between 1998-2023. The analysis included more than 85,000 contacts who tested positive for TB infection at the beginning of the study, among which 1,080 people developed active TB. Low-burden countries were defined as those with fewer than 20 cases of new TB disease per 100,000 people annually, while medium-burden countries included those with 20-100 new TB cases per 100,000 people annually, and high-burden countries included those with more than 100 new TB cases per 100,000 people annually.
Most cases of active TB disease occurred within the first two years of infection, supporting past research that also indicates this period is a crucial time for people with TB infections to receive treatment. People in medium-burden and low-burden settings who completed the medication course developed the strongest protection and had a lower risk of developing TB within the first year of infection compared to people who only partially completed the course—but within two years of infection, the risk among these groups was not meaningfully different. Both of these groups still showed strong protection for at least eight years.
The researchers say more data is needed to understand why protection waned faster in high-burden settings.
“It is understood that high-burden settings will have higher rates of re-exposures and reinfections, and that is likely driving a large portion of the waning of effects we observed,” Ms. Linde says. “Once you complete a course of TPT, those antibiotics leave your system and you aren’t protected from getting infected again. There is also some conjecture in the literature that TPT might actually be less effective at killing all the TB bacteria among people in higher-burden settings, who may have had multiple exposures and carry a relatively larger baseline bacterial load, but unfortunately our data can’t tease apart these possible mechanisms.”
The team hopes this new insight can encourage continued expansion of TPT across the globe and guide high-burden countries to offer this treatment in tandem with other health-protective resources to detect, prevent, and treat TB.
“TPT is a critical tool for combatting the spread of TB worldwide, and we aim to continue studying how to best target TPT to achieve the greatest impact in reducing TB incidence,” says Ms. Linde.
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About Boston University School of Public Health
Founded in 1976, Boston University School of Public Health is one of the top ten ranked schools of public health in the world. It offers master's- and doctoral-level education in public health. The faculty in six departments conduct policy-changing public health research around the world, with the mission of improving the health of populations—especially the disadvantaged, underserved, and vulnerable—locally and globally.
The Lancet Respiratory Medicine
Meta-analysis
People
Duration of effectiveness of tuberculosis preventive treatment across various tuberculosis burden settings: a systematic review and individual-participant meta-analysis
18-Sep-2026
JIC was supported by the US National Institutes of Health (NIH; grant K23AI186597). CRH is on the Data Safety Monitoring Board for the SUDOCU, ACT5, and Decision trials, is Chair of the Trial Steering Committee for UNITE4TB, and was a member of the Board of Directors of the International Union Against Tuberculosis and Lung Disease from 2019 to 2025. IA was supported by the UK National Institute for Health and Care Research (NIHR). MCB was supported by the US NIH (grants U01 AI057786 and U19 AI076217). FA was supported by the Brunei Darussalam Ministry of Health (Brunei Centre for Disease Control). DB-B had grant funding from bioMérieux Colombia, unrelated to the current manuscript. TFB was supported by the Canadian Institutes of Health Research. RKG was supported by grant funding from the UK NIHR, the Royal Society, and the Wellcome Trust, unrelated to the current manuscript. NM was supported by US NIH funding, is a board member of Wits Health Consortium, and has a leadership role at the Setshaba Research Centre. VM was supported by funding from the US NIH, unrelated to the current manuscript. SN has received honoraria from the Karolinska Institutet and Gothia Kompetens, and has indirect shares in AstraZeneca. YS was supported by funding from the US NIH (grants R35GM146612, R01AI170116, and 75N93019C00052), unrelated to the current manuscript. CS was supported by the US NIH (grants N01-AI95383 and N01-AI70022). JAV is a federal employee with the US National Center for Emerging and Zoonotic Infectious Diseases (NCEZID) at the Centers for Disease Control and Prevention (CDC). This work was not funded or sponsored by CDC, and the data, results, and opinions included in this manuscript do not reflect the views of positions of this federal agency or the US Government. JG was supported by funding from the US NIH, unrelated to the current manuscript. All other authors declare no competing interests.