[Purpose/significance] A single emergency may further develop and trigger a series of secondary and derived events, which may expand the scope and impact of the event. Thus, it is of great significance to study the detection of the secondary and derived events of emergencies. [Method/process]In this study, we obtained 133 947 microblog entries related to the Changchun Changsheng vaccine event in 2018, and extracted the feature words of the microblog text at each life cycle stage of the event based on the four-stage theory of crisis communication. The word2vec and Kmeans clustering algorithm was used to identify the topics of the microblog text at each life cycle stage of the event. The influence of each topic was calculated based on the H-index to reveal the salient topics. The determination rules for the secondary and derived events were also constructed to detect those events. [Result/conclusion]The results of this study indicate that there are 17 secondary and derived events in the Changchun Changsheng vaccine event. This study
constructs the determination rules and methods of identifying secondary and derivative events, which can enrich the theory and method of emergency management. It can help grasp the occurrence mechanism of secondary and derived events of emergencies, and improve the ability of emergency response.