Pan XX, Chen Y, Wang AH, Wang JM, Ye LX, Gu SH, Fang T, Xu GZ. [Study on transmission dynamic of 15 clusters of COVID-2019 cases in Ningbo].
Zhonghua Liu Xing Bing Xue Za Zhi 2021;
41:2010-2014. [PMID:
32397699 DOI:
10.3760/cma.j.cn112338-20200330-00466]
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Abstract
Objective: To describe the basic characteristics of clusters of coronavirus diseases 2019 (COVID-19) cases in Ningbo, Zhejiang province, and evaluate the generation time (Tg) and basic reproduction number (R(0)) of COVID-19. Methods: The basic information and onset times of the clusters of COVID-19 cases in Ningbo were investigated, the inter-generational interval of the cases were fitted by using gamma distribution, and the R(0) was calculated based on the SEIR model. Results: In the 15 clusters of COVID-19 cases, a total of 52 confirmed cases, 5 cases of nucleic acid-positive asymptomatic cases. The cases occurred from January 23 to February 4, the cases were mainly women. The incubation period was (6.11±3.38) days, and the median was 5 days. The Tg was (6.93±3.70) days. There were no significant differences in Tg between age group<60 years and age group 60 years and above, and between men and women (P=0.551). According to the Tg calculated in this paper, the R(0) of COVID-19 in Ningbo was 3.06 (95%CI: 2.64- 3.51); according to the reported case transmission interval of 7.5 days in the literature, the R(0) was 3.32 (95%CI: 2.51-9.38). Conclusion: There is no age and gender specific differences in the Tg of clusters of COVID-19 cases in Ningbo, and COVID-19 has high infectivity and spreading power in early phase.
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