By end of October 2020, the COVID-19 pandemic has taken a tragic toll of 1150 000 lives and this number is expected to increase. Despite the pandemic is raging in most parts of the world, in a few countries COVID-19 epidemics subsided due to successful implementations of intervention measures. A unifying perspective of the beginnings, middle stages, and endings of such completed COVID-19 epidemics is developed based on the order parameter and eigenvalue concepts of nonlinear physics, in general, and synergetics, in particular. To this end, a standard susceptible-exposed-infected-recovered (SEIR) epidemiological model is used. It is shown that COVID-19 epidemic outbreaks follow a suitably defined SEIR order parameter. Intervention measures switch the eigenvalue of the order parameter from a positive to a negative value, and in doing so, stabilize the COVID-19 disease-free state. The subsiding of COVID-19 epidemics eventually follows the remnant of the order parameter of the infection dynamical system. These considerations are illustrated for the COVID-19 epidemic in Thailand from January to May 2020. The decay of effective contact rates throughout the three epidemic stages is demonstrated. Evidence for the sign-switching of the dominant eigenvalue is given and the order parameter and its stage-3 remnant are identified. The presumed impacts of interventions measures implemented in Thailand are discussed in this context.

到 2020 年 10 月下旬，COVID-19 大流行已造成 115 万人丧生，预计这一数字还会增加。尽管大流行在世界大部分地区肆虐，但在少数国家，由于成功实施了干预措施，COVID-19 流行病有所缓解。此类已完成的 COVID-19 流行病的开始、中间阶段和结束的统一视角是基于非线性物理学（一般而言，特别是协同学）的序参数和特征值概念开发的。为此，使用了标准的易感暴露感染恢复 (SEIR) 流行病学模型。结果表明，COVID-19 流行病的爆发遵循适当定义的 SEIR 顺序参数。干预措施将顺序参数的特征值从正值切换为负值，这样做时，稳定 COVID-19 无病状态。COVID-19 流行病的消退最终遵循感染动力系统的顺序参数的残余。以 2020 年 1 月至 5 月泰国的 COVID-19 流行病为例说明了这些考虑因素。证明了整个三个流行阶段的有效接触率的衰减。给出了主导特征值符号切换的证据，并确定了阶参数及其第 3 阶段的残余。在此背景下讨论了在泰国实施的干预措施的假定影响。证明了整个三个流行阶段的有效接触率的衰减。给出了主导特征值符号切换的证据，并确定了阶参数及其第 3 阶段的残余。在此背景下讨论了在泰国实施的干预措施的假定影响。证明了整个三个流行阶段的有效接触率的衰减。给出了主导特征值符号切换的证据，并确定了阶参数及其第 3 阶段的残余。在此背景下讨论了在泰国实施的干预措施的假定影响。