Effectiveness of Inactivated COVID-19 Vaccines against Delta-Variant COVID-19: Evidence from an Outbreak in Inner Mongolia Autonomous Region, China oleh Chao Ma, Chang Huang, Wenrui Wang, Yudan Song, Xiaofeng Jiang, Xiaoling Tian, Boxi Liu, Fuli Chi, Shengli Lang, Dongyan Liu, Weiwei Sun, Lin Tang, Dan Wu, Yifan Song, Junhong Li, Lance Rodewald, Zundong Yin, Zhijie An