[Practice and understanding of coronavirus disease 2019 epidemiological survey]

Epidemiological survey is a primary measure, following an epidemic detection and report, implemented by agencies for disease control and prevention according to law. It is the key to disposing coronavirus disease 2019 (COVID-19) epidemic and the premise of rapidly controlling this epidemic. In this paper, the essence and fundamental purpose of epidemiological survey in epidemic response was respectively attributed to emergency disposal and epidemic control. Fresh COVID-19 cases experienced by the author were used to introduce "limiting an epidemic to the minimum scale", on-site rapid disposal, developing and verifying a hypothesis, and report writing and suggest some challenges in the survey. This paper highlighted the role of on-site survey that should be not only investigating, but also hypothesizing and, in particular, rapidly disposing. The on-site experience and problems should be particularly transformed into strategies and measures for epidemic prevention and control in time. This paper also emphasized thinking of forming and perfecting the "evidence chain" by systematically checking and laying out the evidence, so as to serve verification of hypotheses. In the face of a once-in-a-century epidemic, extracting the valuable frontline experience of epidemiological survey would be helpful to accurately handle the epidemic situation, maintain the dynamic COVID-zero status, and respond to other major public health events in the future.