Performance of TB Antigen-Based Skin Tests Amongst Healthcare Workers-Sevagram, India, 2023-2024

Background Tuberculosis infection among healthcare workers poses a major occupational health risk in resource-limited, high-burden settings. SIILTIBCY® (CY-TB) is a novel antigen-based skin test for TBI that may offer a simpler, low-cost, field-deployable alternative to laboratory-based interferon-gamma release assays such as QuantiFERON-TB® Gold In-Tube Plus (QFT). Objective To estimate TBI prevalence among HCWs at Mahatma Gandhi Institute of Medical Sciences/Kasturba Hospital Sevagram (MGIMS) and evaluate the diagnostic performance of CY-TB compared to QFT. Methods In a prospective cohort at MGIMS, consenting HCWs without TB disease underwent both CY-TB and QFT testing during July 2023-June 2024. Diagnostic performance of CY-TB was assessed using QFT as the reference standard. Results Of 2071 HCWs offered screening, 1753 (84.6%) consented and 1338 (76.3%) had paired test results. The median age was 29 years (IQR: 19.5, 38.5); 63% were female. Overall prevalence of TB infection was 28.5% (95% CI 26.1-31.0). CY-TB sensitivity and specificity were 76.4% (95% CI 71.6-80.7) and 97.0% (95% CI 95.7-97.9), respectively. The positive and negative predictive values were 90.9% and 91.1%. Conclusions CY-TB performance was comparable to QFT, suggesting it may be a practical, low-cost tool for TB infection screening in resource-limited healthcare settings.