Targeted interventions for tuberculosis elimination in the Republic of Korea’s aging population: clinical impact of latent TB reactivation

Tuberculosis (TB) remains a public health challenge in South Korea, with 58.7% of cases in 2024 among the elderly due to reactivation of latent TB infection (LTBI). We quantified the excess risk of LTBI reactivation in the elderly to inform clinical interventions to eliminate TB. We analyzed 2011–2024 national TB surveillance data, modeling age-specific (<65 vs. ≥65 years) TB dynamics. Using Ensemble Kalman Filter techniques, we estimated the excess risk of LTBI reactivation in the elderly and evaluated targeted interventions to mitigate this risk. The national TB incidence declined (from 100 to 35.2/100,000), but the proportion of elderly cases increased from 30.2% to 58.7% of the total. Elderly patients had a 2.2–9.4 times higher risk of LTBI reactivation than younger adults during the study period. Enhanced elderly screening alone (80% coverage) reduced the projected total incidence to 17.7/100,000 by 2035, while improved treatment compliance (95%) achieved a rate of 19.9/100,000. Combined interventions reached 16.6/100,000, meeting WHO elimination targets, though elderly-specific incidence remained elevated (>50/100,000). While national TB incidence declined from 100 to 35.2 cases per 100,000, the proportion of elderly cases rose from 30.2% to 58.7%. The estimated K remained persistently high overall (>4), indicating sustained reactivation risk in the elderly. Model projections show that reducing LTBI reactivation risk, improving treatment compliance, and enhancing screening are essential to achieve the WHO End TB Strategy target (10 cases/100,000 by 2035). Our results underscore the urgent need for a multifaceted intervention strategy in aging populations to accelerate TB elimination.