The rapid development of the social economy and science and technology has led to more frequent transnational movements of people, goods and vehicles. At the same time, various cross-border risks have significantly increased. The rapid global spread and continuous mutation of Coronavirus Disease 2019 (COVID-19) have again exposed the international community's extreme vulnerability to major transnational public health emergencies. China started a "war against the epidemic" with tight quarantine regulations and border restrictions on people, vehicles and international goods. However, it also revealed the weaknesses in and incapacity for disease prevention and control at ports in terms of obstructed performance of the whole chain of public agencies, incompatible laws and regulations, lack of key technologies, and difficulties in international cooperation. Combined with persuasive data, this paper systematically illustrates how transnational infectious diseases lead humans to be "united by contagion". On this basis, this paper makes a targeted analysis of the deficiencies of port epidemic prevention and control in China's fight against COVID-19 and suggests corresponding countermeasures and reflections.
Keywords: health and quarantine; infectious diseases at port; politicization of epidemic diseases; post-pandemic era; united by contagion.