[Analysis on medical observation of 1 665 close contacts of COVID-19 cases]

Objective: To understand the identification and medical observation of close contacts of COVID-19 cases in a city and provide scientific basis for the adjustment of the epidemic prevention and control strategies. Methods: Descriptive epidemiological methods were used to analyze the general characteristics of all the close contacts of COVID-19 cases in a city. Throat swabs were collected from the close contacts for real-time fluorescent RT-PCR. The confirmed cases were diagnosed according to diagnosis and treatment of COVID-19 (trial version 5). Results: Among the 1 665 close contacts of COVID-19 cases in a city, 10 were diagnosed as COVID-19 cases during the medical observation period, accounting for 30.30% of all the confirmed cases in a city, most of them were close relatives of the confirmed cases. The longest contact time with the confirmed cases was 8 days and the shortest was 0 days. Ten COVID-19 cases in close contacts constituted to six family clusters. Conclusions: In COVID-19 prevention and control in a city, the active tracking of the transmission chains of the confirmed cases and timely identification of the close contacts were conducted. The people who had close contacts with the confirmed COVID-19 cases within 14 days before onset were all placed under medical observation, which played a key role in the effective prevention and control of COVID-19 epidemic in a city. Nearly one third of COVID-19 cases occurred during the medical observation period, so the infection sources were effectively controlled and transmission routes were effectively blocked, which greatly facilitated the prevention of the clusters of COVID-19 cases.