2021年河南省新型冠状病毒Delta变异株肺炎流行病学及分子特征研究

Epidemiological and molecular characteristics of SARS-CoV-2 Delta variant-caused pneumonia in Henan Province in 2021

目的:分析总结2021年河南省新型冠状病毒(severe acute respiratory syndrome coronavirus,SARS-CoV-2)Delta变异株肺炎流行病学及分子特征,为疫情防控提供依据。方法:依据中国疾病预防控制中心(Chinese Centre for Disease Control and Prevention,CDC)反馈测序结果,挑选2021年河南入境和本土病例为SARS-CoV-2 Delta变异株肺炎患者111例,从大疫情网上获得患者基本信息,对年龄、性别、是否接种疫苗、接种剂次、RT-qPCR检测ORF1 ab基因和N基因Ct值在不同性别及不同症状病例间有无差异、患者临床分型等进行统计学分析,对测序结果核苷酸及刺突蛋白(spike protein,S)突变位点进行分析,总结规律。结果:111个病例在不同年龄组间的性别分布差异无统计学意义(χ^(2)=2.217,P=0.529)。不同疫苗接种史人群中的病例类型差异无统计学意义(χ^(2)=12.074,P=0.209)。SARS-CoV-2核酸阳性标本中,大部分标本Ct值分布在较低区间,病毒载量较高。ORF1 ab基因Ct值在不同性别间的差异无统计学意义(χ^(2)=1.646,P=0.439),在无症状感染者、轻型、普通、重型之间差异具有统计学意义(χ^(2)=13.257,P=0.039)。N基因Ct值在不同性别及不同症状病例间差异均无统计学意义(P均>0.05)。本研究的111例患者主要通过密接筛查和全员核酸筛查发现,两者共占总体的62.2%(69例)。测序长度覆盖度基本都大于99%(占90.1%,100/111),核苷酸突变位点总数多为46~50个(86.4%,89/103),S蛋白突变位点总数多为12个(82.5%,85/103)。103株Delta变异株均含有T19R、R158G、L452R、T478K、D614G、P681R、D950N、E156del、F157del这9个突变位点,突变率为100%。结论:2021年河南省SARS-CoV-2 Delta变异株对人群普遍易感;病毒载量高,ORF1 ab基因载量增高会加重临床症状。

Objective To analyze and summarize the epidemiological and molecular characteristics of SARS-CoV-2 Delta variant,a variant of concern(VOC),in Henan Province in 2021 in order to provide a basis for epidemic prevention and control.Methods According to the feedback of sequencing results from Chinese Center for Disease Control and Prevention,111 patients infected with SARS-CoV-2 Delta VOC were selected from the Henan imported and local cases in 2021.Basic patient information was obtained from the pandemic website.The differences in age,gender,vaccination history,the number of vaccine doses and different clinical types were analyzed.Moreover,the differences in RT-qPCR results of ORF1ab gene and N gene Ct values between cases of different genders and symptoms were analyzed statistically.Sequencing results of the nucleotide and S protein mutation sites were analyzed.Results There was no significant difference in the gender distribution of 111 cases between different age groups(χ^(2)=2.217,P=0.529).There was also no significant difference in clinical types between patients with different vaccination history(χ^(2)=12.074,P=0.209).The Ct values of most SARS-CoV-2 nucleic acid-positive specimens were distributed in the lower range and the viral loads were higher.The difference in the Ct value of ORF1ab gene between different gender groups was not statistically significant(χ^(2)=1.646,P=0.439),but were significantly different among asymptomatic,mild,normal,and severe cases(χ^(2)=13.257,P=0.039).There was no significant difference in N gene Ct value among cases of different genders or different symptoms(all P>0.05).The 111 patients in this study were mainly found through close-contact screening and full-staff nucleic acid screening and accounted for 62.2%(69 cases)of the total.The sequencing length coverage was basically greater than 99%(accounting for 90.1%,100/111);the total number of nucleotide mutation sites was mostly in the range of 46-50(86.4%,89/103);the total number of S protein mutation sites was mostly 12(82.5%,85/103).The 103 Delta mutants all contained nine mutation sites,which were T19R,R158G,L452R,T478K,D614G,P681R,D950N,E156del and F157del,with a mutation rate of 100%.Conclusions People were highly susceptible to the SARS-CoV-2 Delta in Henan Province in 2021.High viral load and increase in the ORF1ab gene load would aggravate the clinical symptoms.