Trajectories of interferon-gamma release assay results over two years in independent cohorts from China, South Africa, Tanzania, and the United States by Chen, C, Xue, H, Horsburgh, CR, Amour, M, Hatherill, M, Tameris, M, von Reyn, CF, Rees, C, Shen, Y, McShane, H, García-Basteiro, AL, Liu, D, Wang, Y, Nathavitharana, RR, Graviss, EA, Shao, Y, Liu, Q, Lu, W, Zhu, L, Martinez, L