Impact of COVID-19 on TB care cascade and transmission in Taiwan, an interrupted time series analysis.

BACKGROUND: During the 2020-2021 COVID-19 pandemic, Taiwan's non-pharmaceutical interventions (NPIs) were expected to disrupt tuberculosis (TB) services. Rather than TB service collapse, reductions in TB notifications were observed. This study evaluated the impact of COVID-19 on the TB care cascade and community transmission in Taiwan. METHODS: We conducted an interrupted time series analysis on national registry data (2015-2021) to evaluate the impact of COVID-19 on TB notifications, healthcare utilization, and care cascade timeliness. Latent TB infection (LTBI) positivity among close contacts served as a proxy for transmission. RESULTS: During the two pandemic waves, cumulative TB notifications fell by 6.0% (95% CI: 5.5%-6.5%) and 11.8% (95% CI: 10.9%-12.6%), respectively, paralleling outpatient visit and culture submission declines. Nevertheless, proxies for patient and health system delays, sputum smear-positivity, and care cascade timeliness remained stable. Treatment success and mortality during TB treatment remained consistent with pre-pandemic trends. Community transmission did not uniformly decline; overall LTBI positivity showed wave-specific immediate drops (-8.0% and -14.2%) followed by positive rebound slopes. This "drop-and-rebound" pattern was concentrated predominantly in non-household contacts aged 25-64 years. CONCLUSION: In a setting with effective COVID-19 control via NPIs and a resilient healthcare system, adverse impacts on TB care were minimized, while community transmission declined. Taiwan's experience highlights the collateral benefits of stringent NPIs in mitigating dual infectious disease burdens.