疫情防控常态化期间，人手一码的健康码和遍布各地的核酸检测点无疑构成了中国城市生活的基础设施。在“城市进化”“后种系生成”和“控制论”的交叉视野下，健康码是一种外置免疫器官，它在人类针对新发病毒的自然免疫屏障尚未完全建立起来时，充当着宏观城市层面的外置免疫系统的信息枢纽，尤其是其在疫情监测和识别上的作用，与机体细胞层面的免疫监测和识别，呈现出一定程度上的逻辑上的相似性。与此同时，健康码也以一种外置免疫器官的方式，制造出一系列新型“他者”。自我/他者这个萦绕着整个20世纪的老问题，在健康码所提供的21世纪的特殊社会文化语境中，又获得了重新提出和演绎。健康码首次大规模地让中国老百姓在日常生活层面，经历了一种控制论意义上打破生物和技术边界的状态。其中技术与人的关系，呈现出“后种系生成”或“技术异化”两种可能。我们一方面要肯定技术进步在重大公共卫生事件应急处理创新中的积极作用，另一方面也需反思其中存在的风险。

During the regular epidemic prevention and control, health codes for every hand and nucleic acid testing sites all over the city undoubtedly constitute the infrastructure of urban life in China. In the crossed perspective of “urban evolution”, “epiphylogenesis” and “cybernetics”, the health code is an exteriorized immune information organ. It acts as an information hub of the exteriorized immune system on the macro-level of the city, when the natural immune barrier against emerging viruses has not yet fully established in the human body. Especially in the aspects of epidemic surveillance and recognition, the mechanism of the health code shows a certain degree of logical similarity with the immune surveillance and recognition at the cellular level of the body. At the same time, the health code also creates a new type of “other” in the form of exteriorized immune organ. The old question of self/other of the 20th century is reintroduced and reinterpreted in the special socio-cultural context of the 21st century mediated by the health code. For the first time, the health code allows the Chinese people to experience a cybernetic crossing between biological and technological border in their daily life. The relationship between technology and human beings presents two possibilities: epiphylogenesis or technological alienation. On the one hand, we need to recognize the positive role of technological progress in the innovation of emergency response to major public health events, on the other hand, we also need to reflect on the risks.