2021年12月浙江省三地Delta变异株新型冠状病毒肺炎社区传播疫情流行特征分析

丁哲渊; 吴昊澄; 吴晨; 鲁琴宝; 王心怡; 傅天颖; 杨珂; 林君芬

doi:10.3784/jbjc.202202150040

2021年12月浙江省三地Delta变异株新型冠状病毒肺炎社区传播疫情流行特征分析

Community transmission of COVID-19 outbreaks caused by SARS-CoV-2 Delta variant in 3 areas of Zhejiang, December 2021

摘要

摘要:
目的分析2021年12月浙江省三地Delta变异株新型冠状病毒肺炎（COVID-19）社区传播疫情流行特征。
方法收集中国疾病预防控制信息系统传染病监测系统中报告的本土病例及疾病预防控制中心流调报告信息，描述疫情流行特征，并估计潜伏期、代际间隔和动态再生数（R_t）。
结果 2021年12月4—27日，浙江省宁波、绍兴、杭州市累计报告COVID-19本土病例490例，均为确诊病例。宁波市报告74例，局限在镇海区蛟川街道，发病高峰为12月8—13日，疫情持续13 d，社会面清零用时6 d。绍兴市报告387例，涉及上虞区（99.22%）和越城区（0.78%），发病高峰为12月12—16日，疫情持续21 d，社会面清零用时13 d。杭州市报告29例，涉及5个区，单日发病高峰在12月9日，疫情持续13 d，社会面清零用时4 d。三地病例男、女性别比为0.88∶1，年龄范围为2月龄至98岁，平均年龄为48.4岁，职业以工人（162例）、农民（113例）为主，临床分型以轻型（194例，39.59%）和普通型（291例，59.39%）为主，传播场所主要为家庭和密闭空间，密切接触者/次密切接触者排查和社区筛查是发现病例的主要方式。中位潜伏期为2.53（P₂₅～P₇₅：1.88～3.32） d，中位代际间隔为2.00（P₂₅～P₇₅：1.21～3.09） d。宁波、绍兴、杭州市的R_t在发现疫情后第10、12、11 d降到1以下。
结论本轮疫情传播迅速，家庭、菜场等密闭空间和人群聚集性活动场所的疫情传播风险较高，科学精准排查并有效管控高暴露风险人员有助于疫情的快速控制。

Abstract:
Objective To analyze epidemiological characteristics of COVID-19 outbreaks caused by SARS-CoV-2 Delta variant in 3 areas of Zhejiang province in December 2021.
Methods The case data and epidemiological investigation reports were collected from China's Infectious Disease Information System and local CDCs. The epidemiological characteristics of the cases were described and incubation period, serial interval, and time-varying reproduction numbers (R_t) were estimated.
Results A total of 490 indigenous COVID-19 cases were reported in Ningbo, Shaoxing and Hangzhou of Zhejiang from 4^th December to 27^th December 2021. All the cases were laboratory confirmed. In Ningbo, all the 74 cases lived in Jiaochuan sub-district of Zhenhai district. The incidence peak period was during 8^th−13^th December. The epidemic duration and community transmission duration was 13 days and 6 days. In Shaoxing, 387 cases were reported in Shangyu district (99.22%) and Yuecheng district (0.78%). The incidence peak period was during 12^th−16^th December. The epidemic duration and community transmission duration was 21 days and 13 days. In Hangzhou, 29 cases were reported in five districts. The incidence peak occurred on 9^th December. The epidemic duration and community transmission duration was 13 days and 4 days. Among all the cases, the male to female ratio was 0.88∶1. The age of the cases ranged from two months to 98 years old, and average age was 48.4 years. The cases were mainly workers (162 cases) and farmers (113 cases). The clinical classifications were mainly mild (194 cases, 39.59%) and common (291 cases, 59.39%). Transmissions mainly occurred in families and closed spaces. Close contacts or secondary contacts investigation and community screening were the main ways to find cases. The median of incubation period and serial interval was 2.53 (P₂₅-P₇₅: 1.88–3.32) d and 2.00 (P₂₅–P₇₅: 1.21–3.09) d. R_t decreased below 1 on 10^th, 12^th and 11^th day in Ningbo, Shaoxing and Hangzhou respectively.
Conclusion The COVID-19 outbreaks in 3 areas of Zhejiang spread rapidly. Closed spaces such as home, markets and crowd gathering activity places had high-risk of transmission. Scientific and accurate investigation and effective management of people at high risk for exposure would facilitate the rapid control of the epidemic.

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