In latent TB infection, which short-course regimen is effective for low-risk individuals?

• A. 6 months of isoniazid (6H).
• B. 12 weeks of weekly isoniazid plus rifapentine (3HP).
• C. 12 months of rifampin (12R).
• D. 9 months of isoniazid (9H).

Answer: (B)

The main concept is choosing a latent TB treatment that balances efficacy with short duration to maximize completion and minimize toxicity in low-risk individuals. The 12-week regimen of weekly isoniazid plus rifapentine (3HP) fits this balance best. It provides comparable protection against progression to active TB as longer isoniazid regimens, but because it lasts only three months with weekly dosing, people are far more likely to complete it. The shorter course also tends to reduce the cumulative risk of hepatotoxicity associated with longer isoniazid exposure, while rifapentine allows the total drug exposure to be more limited in time. In contrast, longer regimens like 6 or 9 months of isoniazid require a longer commitment and have higher dropout rates, and a 12-month course of rifampin, though effective, is longer and can involve more drug interaction considerations. So for low-risk individuals, a short, well-tolerated, and highly adherent regimen like 3HP is the most effective choice.