Detection of serum immunoglobulin M and immunoglobulin G antibodies in 2019 novel coronavirus infected patients from different stages oleh Hui-Xia Gao, Ya-Nan Li, Zun-Gui Xu, Yu-Ling Wang, Hai-Bin Wang, Jin-Feng Cao, De-Qin Yuan, Li Li, Yi Xu, Zhi Zhang, Ying Huang, Jian-Hua Lu, Yu-Zhen Liu, Er-Hei Dai, Qiang Shi