ABSTRACT
Objective To analyze the transmission characteristics of family clustering of Corona Virus Disease 2019 (COVID-19) in a town in Tianjin, and to study new epidemiological investigation method applied for the epidemic. Methods The field epidemiological method was applied to investigate confirmed, suspected cases and close contacts of COVID-19, and this clustering epidemic was analyze;and real-time fluorescence PCR (RT-PCR) assay was used for 2019-nCoV nucleic acid testing. Results A total of 11 confirmed cases and 1 suspected case, with three generations of transmission and median generation interval of 6 (2-26) days were involved in current clustering epidemic, the confirmed cases were infectious at the end of the incubation period, the recurrence rate within the families was 33. 33% (19/57), and the epidemiological investigation information acquired through case narration were deviated compared with the trace investigated by police force and the information provided by close contacts. Conclusion The COVID-19 can cause the family clustering spread, and it may infectious at the end of the incubation period. It is necessary to strengthen the trace and management of close contacts during clustering epidemics, and multiple methods adopted making for acquiring epidemiological investigation information. © 2022, Editorial Department of Medical Pest Control. All rights reserved.
ABSTRACT
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.