[Transmission characteristics and risk factors of household COVID-19 clusters caused by 2019-nCoV Omicron variant in Tianjin].

Objective: To understand the transmission characteristics and risk factors of household COVID-19 clusters caused by 2019-nCoV Omicron variant in Tianjin and provide evidence for COVID-19 prevention and control. Methods: Field epidemiological method was used to investigate the epidemiological characteristics of COVID-19 cases, and descriptive analysis was used to describe the epidemiological information. Results: A total of 430 cases were reported in this epidemic in Tianjin, in which 409 cases were included in this study. Among these cases, 70.90% (290/409) occurred in families. The family secondary attack rate was 33.64% The family secondary attack rate in age group 12-17 years (13.79%) was significantly lower than that in age group 18-49 years (36.48%), the OR was 0.378 (95%CI: 0.170-0.840). The logistic regression analysis showed that compared with centralized quarantine, the OR of the index cases found in closed-off/controlled areas and in home quarantine were 2.951 (95%CI:1.322-6.586) and 2.287 (95%CI:1.164-4.495), respectively, compared with the cases without sore throat, the OR of the index cases with sore throat was 3.003 (95%CI: 1.576-5.720), and compared with cases in families without completed COVID-19 vaccinations in all members, the OR of the cases in families with completed COVID-19 vaccinations in all members was 0.268 (95%CI: 0.132-0.552). Conclusions: The risk of household transmission of infection with Omicron variant was high. Detecting the index case in closed-off/controlled areas or in home quarantine and sore throat in index cases were the risk factors of the household transmission, completed COVID-19 vaccination was the protective factor.目的： 了解新型冠状（新冠）病毒Omicron变异株引发天津市家庭聚集性疫情的传播特征及影响因素。 方法： 采用现场流行病学的方法对新冠病毒肺炎病例进行流行病学调查，对流行病学信息进行描述性分析。 结果： 本次疫情天津市共报告430名病例，409名符合纳入标准，70.90%（290/409）发生家庭聚集。家庭续发率为33.64%，12~17岁组首发病例家庭续发率（13.79%）明显低于18~49岁组（36.48%），OR值（95%CI）为0.378（0.170~0.840）。影响家庭聚集发生的多因素logistic回归分析结果显示，首发病例在封/管控区和居家隔离发现较集中隔离发现的OR值（95%CI）分别为2.951（1.322~6.586）和2.287（1.164~4.495），首发病例出现咽部不适较未出现咽部不适的OR值（95%CI）为3.003（1.576~5.720）；家庭内全部完成全程新冠病毒疫苗接种较未全部完成全程新冠病毒疫苗接种的OR值（95%CI）为0.268（0.132~0.552）。 结论： 本次新冠病毒Omicron变异株引发家庭聚集性疫情的风险较高，首发病例在封/管控区和居家隔离发现以及首发病例出现咽部不适是发生家庭聚集的危险因素；家庭内完成全程疫苗接种是发生新冠病毒肺炎家庭聚集的保护因素。.