Epidemiological characteristics of a 2019-nCoV outbreak caused by Omicron variant BF.7 in Shenzhen.
10.3760/cma.j.cn112338-20221031-00926
- Author:
Yan Peng CHENG
1
;
Dong Feng KONG
1
;
Jia ZHANG
1
;
Zi Quan LYU
2
;
Zhi Gao CHEN
1
;
Hua Wei XIONG
1
;
Yan LU
1
;
Qing Shan LUO
1
;
Qiu Ying LYU
1
;
Jin ZHAO
3
;
Ying WEN
1
;
Jia WAN
1
;
Fang Fang LU
4
;
Jian Hua LU
5
;
Xuan ZOU
5
;
Zhen ZHANG
1
Author Information
1. Institute for Infectious Disease Prevention and Control, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China.
2. Central Laboratory,Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China.
3. Institute for AIDS Prevention and Control, Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China.
4. Fuyong Branch Center of Shenzhen Bao'an District Public Health Center, Shenzhen 518103, China.
5. Central Office,Shenzhen Center for Disease Control and Prevention, Shenzhen 518055, China.
- Publication Type:Journal Article
- MeSH:
Male;
Humans;
Female;
SARS-CoV-2;
COVID-19/epidemiology*;
Disease Outbreaks;
Epidemics;
China/epidemiology*
- From:Chinese Journal of Epidemiology
2023;44(3):379-385
- CountryChina
- Language:Chinese
-
Abstract:
Objective: To explore the epidemiological characteristic of a COVID-19 outbreak caused by 2019-nCoV Omicron variant BF.7 and other provinces imported in Shenzhen and analyze transmission chains and characteristics. Methods: Field epidemiological survey was conducted to identify the transmission chain, analyze the generation relationship among the cases. The 2019-nCoV nucleic acid positive samples were used for gene sequencing. Results: From 8 to 23 October, 2022, a total of 196 cases of COVID-19 were reported in Shenzhen, all the cases had epidemiological links. In the cases, 100 were men and 96 were women, with a median of age, M (Q1, Q3) was 33(25, 46) years. The outbreak was caused by traverlers initial cases infected with 2019-nCoV who returned to Shenzhen after traveling outside of Guangdong Province.There were four transmission chains, including the transmission in place of residence and neighbourhood, affecting 8 persons, transmission in social activity in the evening on 7 October, affecting 65 persons, transmission in work place on 8 October, affecting 48 persons, and transmission in a building near the work place, affecting 74 persons. The median of the incubation period of the infection, M (Q1, Q3) was 1.44 (1.11, 2.17) days. The incubation period of indoor exposure less than that of the outdoor exposure, M (Q1, Q3) was 1.38 (1.06, 1.84) and 1.95 (1.22, 2.99) days, respcetively (Wald χ2=10.27, P=0.001). With the increase of case generation, the number and probability of gene mutation increased. In the same transmission chain, the proportion of having 1-3 mutation sites was high in the cases in the first generation. Conclusions: The transmission chains were clear in this epidemic. The incubation period of Omicron variant BF.7 infection was shorter, the transmission speed was faster, and the gene mutation rate was higher. It is necessary to conduct prompt response and strict disease control when epidemic occurs.
