Objective: To analyze the epidemiological characteristics of reinfection of 2019-nCoV and influencing factors, and provide evidence for effective prevention and control of COVID-19 epidemic. Methods: The incidence data of COVID-19 in Ningbo from January 1, 2020 to November 30, 2022 were collected from the infectious disease surveillance system of Chinese information system for disease control and prevention. The incidence of reinfection of 2019-nCoV was investigated by using questionnaire. logistic regression analysis was used to analyze the influences of gender, age, time interval from the first infection, history of underlying disease, 2019-nCoV vaccination dose and disease severity on the reinfection. Results: A total of 897 previous 2019-nCoV infection cases were investigated, of which 115 experienced the reinfection of 2019-nCoV, the reinfection rate was 12.82%. The interval between the two infections M(Q1, Q3) was 1 052 (504, 1 056) days. Univariate analysis showed that age, 2019-nCoV vaccination dose, history of underlying disease, type of 2019-nCoV variant causing the first infection, time interval from the first infection and severity of the first infection were associated with the reinfection rate (all P<0.05). Multivariate logistic regression analysis showed that the risk for reinfection in age group 30- years was higher than that in age group ≥60 years (OR=2.10, 95%CI: 1.11-3.97). No reinfection occurred in those with time interval from the first infection of <6 months, and the risk for reinfection was higher in those with the time interval of ≥12 months than in those with the time interval of 6- months (OR=6.68, 95%CI: 3.46-12.90). The risk for reinfection was higher in the common or mild cases than in the asymptomatic cases (OR=2.64, 95%CI: 1.18-5.88; OR=2.79, 95%CI: 1.27-6.11). Conclusion: The time interval from the first infection was an important influencing factor for the reinfection of 2019-nCoV, and the probability of the reinfection within 6 months was low.
目的： 分析新型冠状病毒（新冠病毒）再感染的流行病学特征及其影响因素，为科学防控新冠病毒感染疫情提供依据。 方法： 在中国疾病预防控制信息系统的传染病监测系统获取2020年1月1日至2022年11月30日宁波市新冠病毒既往感染者的资料，对其再感染状况进行问卷调查，采用多因素logistic回归分析性别、年龄、距初次感染时间间隔、新冠病毒疫苗接种剂次及基础疾病史对新冠病毒再感染的影响。 结果： 共调查897例既往感染者，其中115例再感染者，再感染率为12.82%。再感染者两次感染间隔时间M（Q1，Q3）为1 052（504，1 056）d。单因素分析显示，年龄、新冠病毒疫苗接种剂次、初次感染变异株类型、距初次感染时间间隔、初次感染严重程度与再感染率有关（均P<0.05）。多因素logistic回归分析显示，30~岁组再感染发生风险高于≥60岁组（OR=2.10，95%CI：1.11~3.97）；距初次感染<6个月组无再感染发生，≥12个月组再感染发生风险高于6~个月组（OR=6.68，95%CI：3.46~12.90）；初次感染严重程度为普通型和轻型者再感染发生风险高于无症状感染者（OR=2.64，95%CI：1.18~5.88；OR=2.79，95%CI：1.27~6.11）。 结论： 距初次感染时间间隔是再感染风险的重要影响因素，6个月内出现再感染的概率较低。.