Analysis on the household secondary attack rates of the SARS-CoV-2 Delta variant and the associated factors.
10.3760/cma.j.cn112150-20220526-00535
- VernacularTitle:新型冠状病毒Delta变异株引起的家庭二代续发率及影响因素研究
- Author:
Tao MA
1
;
Song Ning DING
1
;
Jun Jun WANG
2
;
Ya Qiong LIANG
3
;
Qin Yi ZHOU
1
;
Heng Xue WANG
1
;
Yue Yuan ZHAO
1
;
Zi Kang YAN
1
;
Hua Feng FAN
1
;
Nan ZHOU
1
Author Information
1. Department of Acute Infectious Disease Control and Prevention, Nanjing Municipal Center for Disease Control and Prevention, Nanjing 210003, China.
2. Department of Acute Infectious Disease Control and Prevention, Nanjing Municipal Center for Disease Control and Prevention, Nanjing 210003, China Chinese Field Epidemiology Training Program, Chinese Center for Disease Control and Prevention, Beijing 100050, China.
3. Department of Immunization Program, Nanjing Municipal Center for Disease Control and Prevention, Nanjing 210003, China.
- Publication Type:Journal Article
- MeSH:
Male;
Humans;
SARS-CoV-2;
COVID-19/epidemiology*;
Incidence;
Family Characteristics
- From:
Chinese Journal of Preventive Medicine
2023;57(1):8-14
- CountryChina
- Language:Chinese
-
Abstract:
Objective: To evaluate the household secondary attack rates of the SARS-CoV-2 Delta variant and the associated factors. Methods: A COVID-19 outbreak caused by the Delta variant occurred in Nanjing in July 2021. A total of 235 cases with current addresses in Nanjing were reported from 171 households. The subjects in this study were selected from household close contact(s) of infected cases. The information on household index cases and their contacts were collected, and the household secondary attack rate (HSAR) and the risk factors were analyzed by the multi-factor logistic regression model. Results: A total of 234 cases of household close contacts and 64 household secondary cases were reported from 103 households, and the HSAR was 27.4% (64/234, 95%CI:22.0% to 33.4%). The proportions of household size for 2 to 3, 4 to 5, and 6 to 9 were 64.1% (66), 26.2% (27) and 9.7% (10), respectively. A total of 35 cases of household cluster outbreaks were reported (35/103, 34.0%). The number of the first case in the household (FCH) was 103 and males accounted for 27.2% (28 cases), with the median age (Q1, Q3) of 49 (9, 56). The number of household close contacts was 234 and males accounted for 59.0% (138 cases), with the median age (Q1, Q3) of 42 (20, 55) and the median exposure period (Q1, Q3) of 3 (1, 3) days. The multi-factor logistic regression model showed that the higher HSAR was observed in the FCH with the features of airport staff (OR=2.913, 95%CI:1.469-5.774), detection from home quarantine screening (OR=6.795, 95%CI:1.761-26.219) and detection from mass screening (OR=4.239, 95%CI:1.098-16.368). Meanwhile, higher HSAR was observed in cases with longer household exposure (OR=1.221, 95%CI:1.040-1.432), non-vaccination (OR=2.963, 95%CI:1.288-6.813) and incomplete vaccinations (OR=2.842, 95%CI:0.925-8.731). Conclusion: The generation interval of the Delta variant is shortened, and the ability of transmission within the household is enhanced. In the outbreak in Nanjing, the associated factors of HSAR are occupation, detection route, vaccination and exposure period.
