Bai Meiyue felt thrilled when she saw that Chen Yuya had turned into a zombie. In her last life, Chen Yuya was fortunate enough to get enough care and zombie nucleus when she was bitten by a zombie. Because of that, she was able to awaken as a supernatural being.
Chen Yuya was frail to begin with; if not for the fact that Bai Xue didn't trust Bai Meiyue and wanted another option for herself, she would have never handed the zombie nuclei to Chen Yuya.
Though a few ordinary people were able to turn into supernatural beings, in the end it came down to their own immunity system and physical fitness. Only those whose bodies were able to withstand the doomsday virus were able to turn into supernatural beings.