北京市新型冠状病毒Omicron变异株的传播力研究

目的 评估新型冠状病毒Omicron变异株在北京市现有防控措施下的传播力，为做好疫情防控工作提供参考依据。方法 收集北京市2022年3月7-25日报告的78例具有明确传播链的Omicron变异株感染者信息，分别采用Gamma和Weibull分布拟合潜伏期和序列间隔时间，使用马尔科夫链蒙特卡罗算法估计实时再生数（R_t）。结果 Omicron变异株感染者潜伏期M（Q₁，Q₃）为4.0（3.0，6.0）d，序列间隔时间3.0（2.0，5.0）d，序列间隔时间在未完成和已完成全程疫苗接种感染者中M（Q₁，Q₃）分别为2.0（1.0，4.0）d和4.0（2.0，6.0）d（Z=-2.12，P=0.034），儿童和成年人感染者分别为2.0（1.5，3.0）d和4.0（2.0，6.0）d（Z=-2.02，P=0.044），差异均有统计学意义。本轮疫情R_t初始值为4.98（95%CI： 2.22~9.04）。结论 与既往Delta变异株相比，北京市Omicron变异株的传播力较强，应持续做好常态化疫情防控和新型冠状病毒疫苗接种工作，关注儿童易感人群。

Study of transmissibility of 2019-nCoV Omicron variant in Beijing

Objective To evaluate the transmissibility of 2019-nCoV Omicron variant under the current prevention and control strategy in Beijing,and provide evidence for the prevention and control of COVID-19.Methods The information of 78 Omicron variant infection cases involved in clear transmission chains in Beijing during 7-25 March,2022 were collected,the incubation period and serial interval of the disease were fitted by using Gamma and Weibull distribution.Markov Chain Monte Carlo approach was used to estimate the time-varying reproduction number (R_t).Results The median of the incubation period (Q₁,Q₃) of Omicron variant infection was 4.0(3.0,6.0) days,and the serial interval was 3.0(2.0,5.0) days.The median of the serial interval (Q₁,Q₃) was 2.0(1.0,4.0) days in unvaccinated cases and 4.0(2.0,6.0) days in vaccinated cases (Z=-2.12,P=0.034),and 2.0(1.5,3.0) days in children and 4.0(2.0,6.0) days in adults,respectively (Z=-2.02,P=0.044),the differences were significant.The mean of R_t was estimated to be 4.98(95%CI:2.22-9.04) for Omicron variant in this epidemic.Conclusion Omicron variant has stronger transmissibility compared with Delta variant.It is necessary to strengthen the routine prevention and control COVID-19,promote the vaccination and pay close attention to susceptible population,such as children.