北京市新型冠状病毒Omicron BA.2和BF.7变异株感染者潜伏期特征分析

目的 对北京市由新型冠状病毒（新冠病毒）Omicron BA.2和BF.7变异株引起的疫情中的感染者进行流行病学调查,估算2种变异株分支的潜伏期及其影响因素,为新冠病毒传播动力学模型的建立提供基本参数。方法 选取北京市2022年4月（Omicron BA.2变异株）及10月（Omicron BF.7变异株）疫情中具有明确暴露时间和发病时间的感染者进行研究,采用秩和检验对不同变异株的潜伏期差异进行分析。使用Weibull、Gamma和lognormal分布对Omicron变异株的潜伏期分布进行拟合。采用多因素方差分析比较不同年龄、性别、变异株类型及疫苗接种状态下的潜伏期。结果 共纳入64例BA.2变异株感染者及58例BF.7变异株感染者。BA.2和BF.7变异株感染者潜伏期M（Q₁,Q₃）分别为3.00（3.00,4.00）d和3.00（2.00,3.25）d。lognormal分布的拟合效果最佳。多因素方差分析结果显示,不同类型的Omicron变异株潜伏期存在一定差异,与BA.2变异株感染者相比,BF.7变异株感染者的潜伏期更短。结论 Omicron BF.7变异株感染者潜伏期较BA.2变异株的潜伏期短。

Comparison of incubation periods of infections of Omicron variants BA.2 and BF.7 in Beijing

Objective To understand the incubation periods of infections of Omicron variants BA.2 and BF.7 in two COVID-19 epidemics and related factors in Beijing and provide basic parameters for the establishment of 2019-nCoV dynamic transmission model. Methods The COVID-19 cases with specific exposure time and onset time in the Omicron variant BA.2 infection epidemic in April 2022 and in the Omicron variant BF.7 infection epidemic in October 2022 in Beijing were included in the analysis. The rank-sum test was conducted to estimate the differences in the incubation period between two types of infections. The incubation period distribution of the Omicron variant infection was fitted by using Weibull, Gamma and lognormal distributions. Multivariate analysis of variance was conducted to assess the effects of age, sex, variant type and vaccination status on the incubation periods. Results A total of 64 cases of variant BA.2 infection and 58 cases of variant BF.7 infection were included. The M(Q₁, Q₃) of the incubation period was 3.00 (3.00, 4.00) days for BA.2 infection and 3.00 (2.00, 3.25) days for BF.7 infection. The lognormal distribution was the best fit. Multivariate analysis of variance showed that there were some differences in the incubation periods between two types of infections of Omicron variants, and the incubation period of variant BF.7 infection was shorter than that of variant BA.2 infection.Conclusion Omicron variant BF.7 infection had shorter incubation period compared with Omicron variant BA.2 infection.