Symptomatic COVID-19 in University Students: A School-Wide Web-Based Questionnaire Survey during the Omicron Variant Outbreak

Aim: To detect risk and preventive factors associated with the Omicron variant infection in university students, a combination of a web-based survey and multivariate logistic regression analysis was introduced as the front-line initiatives by the school health practitioners. Design: Questionnaire survey. Methods: The school-wide web-based questionnaire survey was conducted among our university students as a part of the annual health check-up in April, 2023. The positive outcome was confined to the first symptomatic COVID-19 onset during the Omicron variant outbreak. Results: In this self-administered survey, risk or protective associations were merely estimated statistically in university students (n = 5406). In measured factors, karaoke and club/group activities could maintain the statistical significance in adjusted odds ratios (ORs) as relative risk factors, and science course, measles/ rubella (MR) vaccination, and COVID-19 vaccination remained as relative protective factors in adjusted OR analyses. Club/group activities with member gathering and karaoke sing-along sessions in university students may frequently have WHO’s three Cs. These risk factors are still important topics for the infection control of COVID-19 in university students. Together with some recent reports from other researchers, the significant protective role of MR vaccine in our survey warrants further clinical investigation. If the breakthrough infection continuously constitutes the majority of infection, real data in test-negative case-control or web-based questionnaire design continue to be important for statistical analysis to determine the minimal requirement of our strategies which may be equivalent to or replace COVID-19 vaccines.

Chest computed tomography findings of the Omicron variants of SARS-CoV-2 with different cycle threshold values

BACKGROUND The Omicron variant of severe acute respiratory syndrome coronavirus 2(SARSCoV-2)mainly infects the upper respiratory tract.This study aimed to determine whether the probability of pulmonary infection and the cycle threshold(Ct)measured using the fluorescent polymerase chain reaction(PCR)method were related to pulmonary infections diagnosed via computed tomography(CT).AIM To analyze the chest CT signs of SARS-CoV-2 Omicron variant infections with different Ct values,as determined via PCR.METHODS The chest CT images and PCR Ct values of 331 patients with SARS-CoV-2Omicron variant infections were retrospectively collected and categorized into low(<25),medium(25.00-34.99),and high(≥35)Ct groups.The characteristics of chest CT images in each group were statistically analyzed.RESULTS The PCR Ct values ranged from 13.36 to 39.81,with 99 patients in the low,155 in the medium,and 77 in the high Ct groups.Six abnormal chest CT signs were detected,namely,focal infection,patchy consolidation shadows,patchy groundglass shadows,mixed consolidation ground-glass shadows,subpleural interstitial changes,and pleural changes.Focal infections were less frequent in the low Ct group than in the medium and high Ct groups;these infections were the most common sign in the medium and high Ct groups.Patchy consolidation shadows and pleural changes were more frequent in the low Ct group than in the other two groups.The number of patients with two or more signs was greater in the low Ct group than in the medium and high Ct groups.CONCLUSION The chest CT signs of patients with pulmonary infection caused by the Omicron variants of SARSCoV-2 varied depending on the Ct values.Identification of the characteristics of Omicron variant infection can help subsequent planning of clinical treatment.

Omicron variant (B.1.1.529) of SARS-CoV-2: Mutation, infectivity, transmission, and vaccine resistance

The appearance of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variant Omicron(B.1.1.529)has caused panic responses around the world because of its high transmission rate and number of mutations.This review summarizes the highly mutated regions,the essential infectivity,transmission,vaccine breakthrough and antibody resistance of the Omicron variant of SARSCoV-2.The Omicron is highly transmissible and is spreading faster than any previous variant,but may cause less severe symptoms than previous variants.The Omicron is able to escape the immune system’s defenses and coronavirus disease 2019 vaccines are less effective against the Omicron variant.Early careful preventive steps including vaccination will always be key for the suppression of the Omicron variant.

Efficacyand Safetyof Huashi Baidu Granules in Treating Patients with SARS-CoV-2Omicron Variant: A Single-Center Retrospective Cohort Study

Objective:To evaluate the efficacy and safety of Huashi Baidu Granules(HSBD)in treating patients with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Omicron variant.Methods:A single-center retrospective cohort study was conducted during COVID-19 Omicron epidemic in the Mobile Cabin Hospital of Shanghai New International Expo Center from April 1st to May 23rd,2022.All COVID-19 patients with asymptomatic or mild infection were assigned to the treatment group(HSBD users)and the control group(non-HSBD users).After propensity score matching in a 1:1 ratio,496 HSBD users of treatment group were matched by propensity score to 496 non-HSBD users.Patients in the treatment group were administrated HSBD(5 g/bag)orally for 1 bag twice a day for 7 consecutive days.Patients in the control group received standard care and routine treatment.The primary outcomes were the negative conversion time of nucleic acid and negative conversion rate at day 7.Secondary outcomes included the hospitalized days,the time of the first nucleic acid negative conversion,and new-onset symptoms in asymptomatic patients.Adverse events(AEs)that occurred during the study were recorded.Further subgroup analysis was conducted in vaccinated(378 HSBD users and 390 non-HSBD users)and unvaccinated patients(118 HSBD users and 106 non-HSBD users).Results:The median negative conversion time of nucleic acid in the treatment group was significantly shortened than the control group[3 days(IQR:2-5 days)vs.5 days(IQR:4-6 days);P<0.01].The negative conversion rate of nucleic acid in the treatment group were significantly higher than those in the control group at day 7(91.73%vs.86.90%,P=0.014).Compared with the control group,the hospitalized days in the treatment group were significantly reduced[10 days(IQR:8-11 days)vs.11 days(IQR:10.25-12 days);P<0.01].The time of the first nucleic acid negative conversion had significant differences between the treatment and control groups[3 days(IQR:2-4 days)vs.5 days(IQR:4-6 days);P<0.01].The incidence of new-onset symptoms including cough,pharyngalgia,expectoration and fever in the treatment group were lower than the control group(P<0.05 or P<0.01).In the vaccinated patients,the median negative conversion time and hospitalized days were significantly shorter than the control group after HSDB treatment[3days(IQR:2-5days)vs.5 days(IQR:4-6 days),P<0.01;10 days(IQR:8-11 days)vs.11 days(IQR:10-12 days),P<0.01].In the unvaccinatedpatients,HSBD treatment efficiently shorten the median negative conversion time and hospitalized days[4 days(IQR:2-6 days)vs.5 days(IQR:4-7 days),P<0.01;10.5 days(IQR:8.75-11 days)vs.11.0 days(IQR:10.75-13 days);P<0.01].No serious AEs were reported during the study.Conclusion:HSBD treatment significantly shortened the negative conversion time of nuclear acid,the length of hospitalization,and the time of the first nucleic acid negative conversion in patients infectedwith SARS-COV-2Omicronvariant(Trial registry No.ChiCTR2200060472).

Concomitant and sequential administration of nirmatrelvir-ritonavir and azvudine in patients with COVID-19 caused by the Omicron variant: Safety and efficacy

Background:This study assessed the safety and efficacy of nirmatrelvir-ritonavir(Paxlovid®)and azvudine when administered sequentially or concomitantly in patients with coronavirus 2019(COVID-19)caused by the Omicron variant.Methods:Ninety-three patients confirmed to be infected with the Omicron variant by nucleic acid detection were retrospectively investigated.Informa-tion was collected on general health status,medication,and adverse drug reactions(ADRs)according to whether nirmatrelvir-ritonavir and azvudine were administered sequentially or concomitantly.Data on times of onset,clinical manifestations,and outcomes of ADRs and on conversion to a nega-tive nucleic acid test were also recorded.Results:Possible ADRs were recorded in 41 patients(44.1%).There were 22 gastrointestinal reactions in 18 patients and 18 hematological abnormalities in 16 after sequential or concomitant treatment with nirmatrelvir-ritonavir and azvudine.Liver enzyme levels increased in nine cases and creatinine clearance decreased in two.Cases of atrial fibrillation(n=1),sleep disorder(n=2),rash(n=2),dizziness(n=1),and weakness(n=5)were also documented.Only vomiting,poor appetite,diarrhea,xerostomia,bitter taste,and rash were considered probable ADRs;others were thought to be possible ADRs.In all cases,the nucleic acid test did not turn negative after the first antiviral was applied.The nucleic acid test of 28 patients did not turn negative before discharge.The remaining 65 patients(69.9%)returned a negative nucleic acid test after receiving the second antiviral agent.Conclusions:Treatment with nirmatrelvir-ritonavir and azvudine is safe and effective whether administered sequentially or concomitantly in patients with COVID-19 caused by the Omicron variant.

A human monoclonal antibody neutralizes SARS-CoV-2 Omicron variants bytargeting the upstream region of spike protein HR2 motif

The continuous emergence of new severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)variants meansthere is a need to explore additional strategies to develop broad-spectrum vaccines or therapeutics for individuals remaining at risk of coronavirus disease 2019(COVID-19).Neutralizing monoclonal antibody(mAb)that binds to theconserved S2 subunit of the SARS-CoV-2 spike(S)protein alone,or in combination with mAb that binds to the receptor-binding domain(RBD)of S protein,might be effective in eliciting protection from infection by a variety of SARS-CoV2 variants.Using high-throughput single-cell immunoglobulin sequencing of B cells from COVID-19-convalescent donors,we identified a high-affinity S2-specific mAb-39,that could inhibit original SARS-CoV-2 strain,Omicron BA.1,BA.2.86,BA.4,BA.5,and EG.5.1 S protein-mediated membrane fusion,leading to the neutralization of these pseudoviralinfections.Moreover,mAb-39 could also improve the neutralizing activity of anti-RBD antibody against the highlyneutralization-resistant Omicron variants.Molecular docking and point mutation analyses revealed that mAb-39 recognized epitopes within the conserved upstream region of the heptad repeat 2(HR2)motif of the S2 subunit.Collectively,these findings demonstrate that targeting the conserved upstream region of the HR2 motif(e.g.,using mAbs)provides anovel strategy for preventing the infection of SARS-CoV-2 and its variants.

Lab results of COVID-19 patients:Omicron vs delta variants

BACKGROUND The coronavirus disease 2019(COVID-19)virus has been a world-known pan-demic since February 2020.Multiple variances had been established;the most common variants in Israel were omicron and delta.AIM To analyze and compare laboratory values in the"omicron"and"delta"variants of the coronavirus by conducting follow-up examinations and laboratory audits on COVID-19 patients admitted to our institution.METHODS A retrospective study,two groups,50 patients in each group.Patients examined positive for COVID-19 were divided into groups according to the common variant at the given time.We reviewed demographic data and laboratory results such as complete blood count and full chemistry,including electrolytes and coagulation parameters.RESULTS The mean age was 52%,66.53±21.7 were female.No significance was found comparing laboratory results in the following disciplines:Blood count,hemo-globin,and lymphocytes(P=0.41,P=0.87,P=0.97).Omicron and delta variants have higher neutrophil counts,though they are not significantly different(P=0.38).Coagulation tests:Activated paritial thromoplastin test and international normalized ratio(P=0.72,P=0.68).We found no significance of abnormality for all electrolytes.CONCLUSION The study compares laboratory results of blood tests between two variants of the COVID-19 virus–omicron and delta.We found no significance between the variants.Our results show the need for further research with larger data as well as the need to compare all COVID-19 variants.

Clinical characteristics of pediatric cases infected with the SARS-CoV-2 Omicron variant in a tertiary children's medical center in Shanghai,China

Background The number of pediatric cases of infection with the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)Omicron variant has increased.Here,we describe the clinical characteristics of children in a tertiary children's medical center in Shanghai.Methods A total of 676 pediatric coronavirus disease 2019(COVID-19)cases caused by the Omicron variant who were admitted to the Shanghai Children's Medical Center from March 28 to April 30,2022 were enrolled in this single-center,prospective,observational real-world study.Patient demographics and clinical characteristics,especially COVID-19 vaccine status,were assessed.Results Children of all ages appeared susceptible to the SARS-CoV-2 Omicron variant,with no significant difference between sexes.A high SARS-CoV-2 viral load upon admission was associated with leukocytopenia,neutropenia,and thrombocytopenia(P=0.003,P=0.021,and P=0.017,respectively)but not with physical symptoms or radiographic chest abnormalities.Univariable linear regression models indicated that comorbidities(P=0.001)were associated with a longer time until viral clearance,and increasing age(P<0.001)and two doses of COVID-19 vaccine(P=0.001)were associated with a shorter time to viral clearance.Multivariable analysis revealed an independent effect of comorbidities(P<0.001)and age(P=0.003).The interaction effect between age and comorbidity showed that the negative association between age and time to virus clearance remained significant only in patients without underlying diseases(P<0.001).Conclusion This study describes the clinical characteristics of children infected with the Omicron variant of SARS-CoV-2 and calls for additional studies to evaluate the effectiveness and safety of vaccination against COVID-19 in children.

Omicron variants breakthrough infection elicited higher specific memory immunity than third dose booster in healthy vaccinees

Homologous booster,heterologous booster,and Omicron variants breakthrough infection(OBI)could improve the humoral immunity against Omicron variants.Questions concerning about memory B cells(MBCs)and T cells immunity against Omicron variants,features of long-term immunity,after booster and OBI,needs to be explored.Here,comparative analysis demonstrate antibody and T cell immunity against ancestral strain,Delta and Omicron variants in Omicron breakthrough infected patients(OBIPs)are comparable to that in Ad5-nCoV boosted healthy volunteers(HVs),higher than that in inactivated vaccine(InV)boosted HVs.However,memory B cells(MBCs)immunity against Omicron variants was highest in OBIPs,followed by Ad5-nCoV boosted and InV boosted HVs.OBIPs and Ad5-nCoV boosted HVs have higher classical MBCs and activated MBCs,and lower naïve MBCs and atypical MBCs relative to both vaccine boosted HVs.Collectively,these data indicate Omicron breakthrough infection elicit higher MBCs and T cells against SARS-CoV-2 especially Omicron variants relative to homologous InV booster and heterologous Ad5-nCoV booster.

Mathematical modeling for Delta and Omicron variant of SARS-CoV-2 transmission dynamics in Greece

A compartmental,epidemiological,mathematical model was developed in order to analyze the transmission dynamics of Delta and Omicron variant,of SARS-CoV-2,in Greece.The model was parameterized twice during the 4th and 5th wave of the pandemic.The 4th wave refers to the period during which the Delta variant was dominant(approximately July to December of 2021)and the 5th wave to the period during which the Omicron variant was dominant(approximately January to May of 2022),in accordance with the official data from the National Public Health Organization(NPHO).Fitting methods were applied to evaluate important parameters in connection with the transmission of the variants,as well as the social behavior of population during these periods of interest.Mathematical models revealed higher numbers of contagiousness and cases of asymptomatic disease during the Omicron variant period,but a decreased rate of hospitalization compared to the Delta period.Also,parameters related to the behavior of the population in Greece were also assessed.More specifically,the use of protective masks and the abidance of social distancing measures.Simulations revealed that over 5,000 deaths could have been avoided,if mask usage and social distancing were 20%more efficient,during the short period of the Delta and Omicron outbreak.Furthermore,the spread of the variants was assessed using viral load data.The data were recorded from PCR tests at 417 Army Equity Fund Hospital(NIMTS),in Athens and the Ct values from 746 patients with COVID-19 were processed,to explain transmission phenomena and disease severity in patients.The period when the Delta variant prevailed in the country,the average Ct value was calculated as 25.19(range:12.32e39.29),whereas during the period when the Omicron variant prevailed,the average Ct value was calculated as 28(range:14.41e39.36).In conclusion,our experimental study showed that the higher viral load,which is related to the Delta variant,may interpret the severity of the disease.However,no correlation was confirmed regarding contagiousness phenomena.The results of the model,Ct analysis and official data from NPHO are consistent.

An RBD bispecific antibody effectively neutralizes a SARS-CoV-2 Omicron variant

Potent neutralizing antibodies(nAbs)against SARS-CoV-2 are a promising therapeutic against the ongoing COVID-19 pandemic.However,the continuous emergence of neutralizing antibody escape variants makes it challenging for antibody therapeutics based on monospecific nAbs.Here,we generated an IgG-like bispecific antibody(bsAb),Bi-Nab,based on a pair of human neutralizing antibodies targeting multiple and invariant sites of the spike receptor binding domain(RBD):35B5 and 32C7.We demonstrated that Bi-Nab exhibited higher binding affinity to the Delta spike protein than its parental antibodies and presented an extended inhibition breadth of preventing RBD binding to angiotensin-converting enzyme 2(ACE2),the cellular receptor of SARS-CoV-2.In addition,pseudovirus neutralization results showed that Bi-Nab improved the neutralization potency and breadth with a lower half maximum inhibitory concentration(IC50)against wild-type SARS-CoV-2,variants being monitored(VBMs)and variants of concern(VOCs).Notably,the IgG-like Bi-Nab enhanced the neutralizing activity against Omicron variants with potent capabilities for transmission and immune evasion in comparison with its parental monoclonal antibody(mAb)32C7 and a cocktail(with the lowest IC50 values of 31.6 ng/mL against the Omicron BA.1 and 399.2 ng/mL against the Omicron BA.2),showing evidence of synergistic neutralization potency of Bi-Nab against the Omicron variants.Thus,Bi-Nab represents a feasible and effective strategy against SARS-CoV-2 variants of concern.

上海市某方舱医院2897例新型冠状病毒Omicron变异株轻型/无症状感染者住院时间影响因素分析

目的探讨上海市某方舱医院新型冠状病毒奥密克戎(Omicron)变异株轻型/无症状感染者住院时间的影响因素。方法回顾性收集上海宝山泾灿路(罗泾京东)方舱医院收治的2897例Omicron变异株轻型/无症状感染者的病历资料,分析其一般资料、住院时间等基本情况,探究不同特征的新冠病毒Omicron变异株感染者住院时间差异,采用多重线性回归方法分析住院时间的影响因素。根据单因素分析结果,采用二元logistic回归分析住院时间≥14 d可能的影响因素。结果2897例Omicron变异株轻型/无症状感染者的平均住院时间为(9.1±4.6)d,不同年龄段、入舱前核酸阳性时间以及伴有咳嗽、咳痰、咽痛、发热、流涕、鼻塞、口干咽燥、头痛、乏力、肌痛、腹泻、恶寒、恶心呕吐、头晕症状的感染者住院时间不同,差异具有统计学意义(P<0.05)。多重线性回归结果显示,年龄增加、患有糖尿病史以及咽痛、发热、流涕、肌痛症状会增加住院天数,而入舱前核酸阳性时间长则会减少住院天数。住院时间≥14 d者,高龄、糖尿病史以及出现咽痛、发热、口干咽燥、肌痛、恶心呕吐症状的占比更高,入舱前核酸阳性时间相对更短,接种2针及以上疫苗占比更低,差异具有统计学意义(P<0.05)。二元Logistic回归结果显示,高龄、入舱前核酸阳性时间短、糖尿病史以及发热和口干咽燥症状可能是导致住院时间超过14 d的危险因素,接种2针及以上疫苗可能是保护因素。结论Omicron变异株轻型/无症状感染者平均住院时间约为9 d,高龄、疫苗接种2针及以上、患有糖尿病史、入舱前核酸阳性时间短以及咽痛、发热、流涕、口干咽燥、肌痛等正气虚衰、病邪入里、化热伤阴表现对于住院时间可能产生重要影响。通过尽早识别核酸转阴慢、住院时间长的高危患者,以期为缩短核酸转阴时间、指导重点人群精准防控提供指导方向。

1起由冷链产品引起的新型冠状病毒Omicron BA.2.3.7感染的传播链和基因序列分析

目的对福建省福州市M区1起由进口冷链产品引起的新型冠状病毒暴发疫情进行溯源及基因序列分析。方法收集2022年9月6日至9月9日期间M区新冠疫情中全部感染者(8名)以及1份阳性冷链产品样本拭子,进行流行病学调查,对采集到的样本进行实时荧光定量PCR检测,对3例阳性感染者和1份冷链产品样本进行全基因组序列测序分析。结果该起疫情共有8人感染,均为无症状感染者,4条全基因组序列高度同源,共享75个的核苷酸突变位点,共享55个氨基酸突变位点,且符合谱系BA.2.3.7的特征。结论本次疫情由未有效防护的工人暴露于污染了新型冠状病毒Omicron BA.2.3.7的进口冷链产品所引起。

SARS-CoV-2 Omicron变异株多重微滴式数字PCR定量方法的建立及应用

【目的】为建立精准、高效的多重微滴式数字PCR(droplet digital PCR,ddPCR)定量分析检测方法,开发可同时鉴别新型冠状病毒(severe acute respiratory syndrome coronavirus 2,SARS-CoV-2)ORF1ab基因、N基因、E基因以及Omicron变异株S基因的检测体系,提高病毒性传染疾病的诊断效率及传播风险监测能力。【方法】通过筛选保守基因序列并设计特异性引物与探针,优化反应体系和扩增程序,对该方法的特异性、灵敏度及稳定性进行评价。以临床样本为实验材料,利用建立的ddPCR方法进行检测和验证,确定阳性检出率。【结果】多重ddPCR反应体系中,各对引物探针对目的片段均能有效扩增,SARS-CoV-2 ORF1ab基因、N基因、E基因以及Omicron变异株S基因灵敏度检测下限分别为0.59、0.68、1.44、1.03 copies/μL。在20份临床样本的核酸检测中,共检出16份阳性样本,阳性率达80%(16/20),经荧光定量PCR方法复测符合率一致。【结论】研究建立的多重ddPCR方法特异性强、灵敏度高,可实现对临床样本中微量新冠病毒的精确定量检测。

不同妊娠期感染新型冠状病毒Omicron变异株行剖宫产的妊娠结局及产褥期随访

目的:探讨妊娠不同时期孕妇感染新型冠状病毒(SARS-CoV-2)变异株Omicron并行剖宫产分娩的妊娠结局及产褥期(产后42天)母婴随访情况。方法:选择2022年11月20日至2023年1月25日确诊感染SARS-CoV-2并在广东省妇幼保健院剖宫产分娩的330例孕产妇为研究对象,按孕妇感染孕周分为孕早期组(80例)、孕中期组(151例)、孕晚期组(99例),比较各组孕产妇的一般资料、妊娠并发症和合并症、妊娠结局及产褥期母婴随访情况。结果:孕妇的临床分型为无症状型(9例)和轻型(321例)。孕早期组和孕晚期组妊娠期糖尿病(GDM)发生率高于孕中期组(P<0.05)。3组胎盘早剥、胎儿生长受限、胎儿窘迫、羊水污染、早产、产后出血、巨大儿、低体质量儿发生率及母亲重症监护病房(MICU)转入率、新生儿出生体质量、新生儿窒息率及新生儿重症监护病房(NICU)转入率比较,差异均无统计学意义(P>0.05),孕中期组胎膜早破发生率高于孕晚期组(P<0.05)。产褥期母婴随访结果示,3组产妇子宫切口愈合不良、子宫复旧不良、阴道微生态失衡和新生儿急性上呼吸道感染、肺炎、消化系统疾病、心血管系统疾病发生率比较,差异无统计学意义(P>0.05)。结论:妊娠合并Omicron感染的孕妇绝大多数为轻症型;妊娠不同时期孕妇感染Omicron行剖宫产分娩的妊娠结局及产褥期随访无显著差异;未发现GDM和胎膜早破与不同妊娠期Omicron感染有明显关联。

基于临床及影像特征多元Logistic回归模型在肺部新型冠状病毒Omicron变异株合并细菌感染诊断中的应用

目的探讨基于临床及影像特征多元Logistic回归模型在肺部新冠病毒Omicron变异株合并细菌感染诊断中的应用价值。方法回顾性收集新冠病毒Omicron变异株合并细菌感染者74例,为A组。同时段新冠病毒Omicron变异株感染者90例,为B组。通过单因素与多因素Logistic回归分析,分别构建临床特征、CT影像特征及联合诊断模型。采用受试者操作特征(receiver operating characteristic,ROC)曲线、校准曲线和决策曲线(decision curve analysis,DCA)评估各个模型的预测能力、校准能力和临床效能。采用DeLong检验比较不同模型之间曲线下面积(area under the curve,AUC)的差异。结果多因素Logistic回归显示,慢性阻塞性肺疾病(简称慢阻肺)、重症肺炎、实变影、胸腔积液4个自变量是独立预测因子。临床模型、CT影像模型及联合诊断模型AUC分别为0.893(95%CI:0.843~0.943)、0.838(95%CI:0.773~0.903)、0.948(95%CI:0.915~0.981)。临床与CT影像模型之间差异不具有统计学意义(Z=1.467,P=0.142)。联合诊断模型与临床、CT影像模型间差异均具有统计学意义(Z分别为3.236、4.293,P分别为0.001、<0.001)。校准曲线表明,联合诊断模型预测概率与实际概率之间的良好一致性。DCA示联合诊断模型的净收益最大。结论基于临床及影像学特征的构建的联合诊断模型诊断效能优异,可用于新型冠状病毒Omicron变异株合并细菌感染的诊断与鉴别。

新型冠状病毒Omicron I1566V突变位点MS2噬菌体病毒样颗粒的构建

目的构建新型冠状病毒Omicron I1566V突变位点MS2噬菌体病毒样颗粒。方法选取并合成带有6×His标签的MS2噬菌体的衣壳蛋白(CP)、成熟蛋白(A蛋白)及Omicron I1566V突变基因序列,插入pACYCDuet-1质粒构建重组载体,通过原核系统诱导表达目的蛋白,纯化重组蛋白后利用透射电镜对蛋白质进行物理表征,最后通过反转录聚合酶链反应(RT-PCR)检测病毒样颗粒的热稳定性及耐核酸酶水解能力。结果成功构建包含有6×His标签的CP、A蛋白和Omicron I1566V突变基因序列的重组载体,经限制性内切酶BamHⅠ和KpnⅠ酶切鉴定和测序验证,结果均与预期相符。经诱导并纯化后,通过电镜观察到了大小均匀、直径为23~28 nm的病毒样颗粒,该病毒样颗粒经核酸酶消化后可在37℃条件下稳定储存20 d以上。结论该研究成功利用MS2噬菌体的CP和A蛋白构建了Omicron I1566V突变位点病毒样颗粒,为该突变位点的RT-PCR检测体系提供了可靠的质量保障。

Nasal delivery of broadly neutralizing antibodies protects mice from lethal challenge with SARS-CoV-2 delta and omicron variants

Multiple new variants of severe acute respiratory syndrome coronavirus 2(SARS-Co V-2)have constantly emerged,as the delta and omicron variants,which have developed resistance to currently gained neutralizing antibodies.This highlights a critical need to discover new therapeutic agents to overcome the variants mutations.Despite the availability of vaccines against coronavirus disease 2019(COVID-19),the use of broadly neutralizing antibodies has been considered as an alternative way for the prevention or treatment of SARS-Co V-2 variants infection.Here,we show that the nasal delivery of two previously characterized broadly neutralizing antibodies(F61 and H121)protected K18-h ACE2 mice against lethal challenge with SARS-Co V-2 variants.The broadly protective efficacy of the F61 or F61/F121 cocktail antibodies was evaluated by lethal challenge with the wild strain(WIV04)and multiple variants,including beta(B.1.351),delta(B.1.617.2),and omicron(B.1.1.529)at 200or 1000 TCID_(50),and the minimum antibody administration doses(5-1.25 mg/kg body weight)were also evaluated with delta and omicron challenge.Fully prophylactic protections were found in all challenged groups with both F61 and F61/H121 combination at the administration dose of 20 mg/kg body weight,and corresponding mice lung viral RNA showed negative,with almost all alveolar septa and cavities remaining normal.Furthermore,low-dose antibody treatment induced significant prophylactic protection against lethal challenge with delta and omicron variants,whereas the F61/H121 combination showed excellent results against omicron infection.Our findings indicated the potential use of broadly neutralizing monoclonal antibodies as prophylactic and therapeutic agent for protection of current emerged SARS-Co V-2 variants infection.

Importation of SARS-CoV-2 Omicron variant in Beijing,China

Omicron(B.1.1.529),the fifth variant of concern(VOC)of severe acute respiratory syndrome coronavirus 2(SARS‐CoV‐2),was firstly identified in November 2021 in South Africa.Omicron contains far more genome mutations than any other VOCs ever found,raising significant concerns about its increased transmissibility and immune evasion.Here,we report the importation of the Omicron variant into Beijing,China,in December 2021.Full‐length genome sequences of five imported strains were obtained,with their genetic features characterized.Each strain contained 57 to 61 nucleotide substitutions,39 deletions,and 9 insertions in the genome.Thirty to thirty‐two amino acid changes were found in the spike proteins of the five strains.The phylogenetic tree constructed by the maximum likelihood method showed that all five imported genomes belonged to Omicron(BA.1)(alias of B.1.1.529.1),which is leading to the current surge of coronavirus disease 2019(COVID‐19)cases worldwide.The globally increased COVID‐19 cases driven by the Omicron variant pose a significant challenge to disease prevention and control in China.Continuous viral genetic surveillance and increased testing among international travellers are required to contain this highly contagious variant.

Origin and evolutionary analysis of the SARS-CoV-2 Omicron variant

The severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has evolved rapidly into new variants throughout the pandemic.The Omicron variant has more than 50 mutations when compared with the original wild-type strain and has been identified globally in numerous countries.In this report,we analyzed the mutational profiles of several variants,including the per-site mutation rate,to determine evolutionary relationships.The Omicron variant was found to have a unique mutation profile when compared with that of other SARS-CoV-2 variants,containing mutations that are rare in clinical samples.Moreover,the presence of five mouse-adapted mutation sites suggests that Omicron may have evolved in a mouse host.Mutations in the Omicron receptor-binding domain(RBD)region,in particular,have potential implications for the ongoing pandemic.