基于新冠病毒Delta及Omicron变异株流行特征变化对疫情防控措施优化分析

褚衍茹; 张栋梁; 陈奕; 易波; 雷松; 张言武; 劳旭影; 顾晓敏; 王海波; 丁克琴; 许国章

doi:10.11847/zgggws1139538

基于新冠病毒Delta及Omicron变异株流行特征变化对疫情防控措施优化分析

doi: 10.11847/zgggws1139538

宁波市疾病预防控制中心，宁波 315010

基金项目: 宁波市“科技创新2025”重大专项（2021Z021）；宁波市医疗卫生品牌学科（PPXK2018 – 10）；宁波市应急科技攻关重大专项（2022Z034）；国家自然科学基金（82073514）

详细信息

作者简介:
褚衍茹（1989 – ），女，山东济宁人，博士，医师，研究方向：传染病流行病学

通讯作者:
许国章，E-mail：xugz@nbcdc.org.cn

（张栋梁为本文并列第一作者）
中图分类号: R 183
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出版历程
- 接收日期: 2022-06-21
- 网络出版日期: 2022-07-14
- 刊出日期: 2022-09-30

Optimization of COVID-19 prevention and control measures based on prevalence characteristics of SARS-CoV-2 Delta and Omicron variants: an analysis on surveillance data of Ningbo city

Ningbo Municipal Centre for Disease Control and Prevention, Ningbo, Zhejiang Province 315010, China

摘要

摘要: 目的分析比较宁波市Delta和Omicron变异株引发本土聚集性疫情续发感染者的流行特征，为进一步优化调整新冠肺炎疫情的防控措施提供参考依据。方法以2021年12月1日 — 2022年5月31日宁波市37起本土新冠肺炎疫情中判定为密切接触者（密接）中的171例续发感染者为研究对象，对两种变异株的感染者流行特征进行描述性分析，以与关联病例有明确暴露时间的续发感染者计算潜伏期。结果确诊病例占80.70 %（138/171），无症状感染者占19.30 %（33/171）。Delta和Omicron变异株感染者分别占64.33 %（110/171）和35.67 %（61/171），Omicron变异株的无症状感染者比例高于Delta变异株（54.1 % vs. 0，P < 0.01）。与关联病例有明确暴露时间的22例确诊病例（Delta变异株15例，Omicron变异株 7例）平均潜伏期为（3.45 ± 0.44）d，Delta和Omicron变异株感染者的最长潜伏期分别为8和6 d，平均潜伏期分别为（3.60 ± 0.58）和（3.14 ± 0.63）d，差异无统计学意义（P > 0.05）。Omicron变异株感染者末次暴露至核酸检测首次阳性间隔时间均 ≤ 7d。Omicron变异株感染者核酸检测首次阳性N基因Ct值高于Delta变异株感染者，但平均住院天数少于Delta变异株（P均 < 0.05）。结论 Omicron变异株引发本地疫情的潜伏期 < 7 d且较Delta变异株的致病性低，建议调整密接的管控措施为7 d集中隔离和3 d居家健康监测。
- 新型冠状病毒肺炎 /
- Delta变异株 /
- Omicron变异株 /
- 防控措施
Abstract: Objective To analyze and compare prevalence characteristics of coronavirus disease 2019 (COVID-19) cluster epidemic-related secondary infections caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta and Omicron variant in Ningbo city, and to provide a basis for optimizing and adjusting measures on COVID-19 prevention and control. Methods From the National Information System for Disease Control and Prevention and the reports of field surveys, we extracted the information on 171 COVID-19 cases with SARS-CoV-2 Delta and Omicron variant infection identified among close contacts of 37 local COVID-19 outbreaks in Ningbo city from December 1, 2021 to May 31, 2022. Descriptive analysis was performed to analyze prevalence characteristics of the cases and the incubation period of secondary infection was calculated for the cases with definite exposure time to index cases. Results Of all the cases, 80.70% (n = 138) and 19.30% (n = 33) were confirmed patients and asymptomatic infections; 64.33% (n = 110) and 35.67% (n = 61) were infected with SARS-CoV-2 Delta and Omicron variant, respectively. The proportion of asymptomatic infection was significantly higher in the cases infected with Omicron variant than that in the cases with Delta variant (54.10% vs. 0, P < 0.05). The mean incubation period was 3.45 ± 0.44 days for the 22 confirmed cases (15 and 7 with Delta and Omicron variant infection) after a definite exposure to the index case. The longest incubation period of Delta and Omicron variant infection were 8 and 6 days. The mean incubation period was 3.60 ± 0.58 and 3.14 ± 0.63 days for Delta and Omicron variant infection, with no significant difference (P > 0.05). The interval time between the last exposure and the first positive detection of nucleic acid was ≤ 7 days for the cases with Omicron variant infection. The Ct value of N gene at the first positive nucleic acid detection was significantly higher in the patients with Omicron variant infection than that in those with Delta variant infection (P < 0.05), but the average hospitalization days of the cases with Omicron variant infection was significantly lower than that of cases infected with Delta variant (P < 0.05). Conclusion The incubation period of SARS-CoV-2 Omicron variant infection is less than 7 days and Omicron variant infection is less pathogenic than Delta variant infection. The results suggest that the recommended managent and control measures for close contacts are 7 days′ centralized isolation and 3 days′ home-based health monitoring.
- COVID-19 /
- Omicron variant /
- Delta variant /
- prevention and control measures
注释:

1) （张栋梁为本文并列第一作者）

HTML全文

表 1 不同新冠病毒变异株续发感染者的基本情况比较

项目	Delta变异株（n = 110）		Omicron变异株（n = 61）		χ² 值	P 值
项目	例数	构成比（%）	例数	构成比（%）	χ² 值	P 值
性别					2.231	0.135
男	60	54.55	26	42.62
女	50	45.45	35	57.38
年龄组（岁）					6.817	0.033
≤ 34	30	27.27	28	45.90
34～52	41	37.27	20	32.79
> 52	39	35.46	13	21.31
发现方式					2.941	0.086
集中隔离	77	70.00	50	81.97
非隔离点发现	33	30.00	11	18.03
与关联病例关系					0.227	0.634
家庭成员	27	24.55	17	27.87
非家庭成员	83	75.45	44	72.13
病例类型					73.738	< 0.001
确诊病例	110	100.00	28	45.90
无症状感染者	0	0.00	33	54.10

下载: 导出CSV

表 2 Delta和Omicron变异株续发感染者流行特征

项目	Delta变异株（n = 110）	Omicron变异株（n = 61）	χ²/t/Z 值	P 值
末次暴露与首阳间隔时间（d）			3.166	0.075
≤ 7	102（92.73 %）	61（100 %）
> 7	8（7.27 %）	0（0.00 %）
潜伏期（d）	3.60 ± 0.58	3.14 ± 0.63	0.475	0.640
N基因Ct值	23.00 ± 0.60	26.08 ± 0.89	– 2.957	0.004
住院天数（d）	24.50（20.75，31.00）	18.00（12.00，22.50）	– 5.467	< 0.001

下载: 导出CSV

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