Health system delay and risk factors in pulmonary tuberculosis diagnosis before and during the COVID-19 epidemic: a multi-center survey in China - Fan, Mingkuan; Liu, Yushu; Liu, Kui; Liu, Xiaoqiu; Li, Yuhong; Li, Tao; Zhang, Canyou; Zhang, Hui; Cheng, Jun (Frontiers in Public Health, 2025)