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.

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.

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.

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.

Omicron变异株感染合并热性惊厥儿童的临床特征

目的探讨儿童Omicron变异株感染合并热性惊厥(FS)患儿的临床特征。方法回顾性分析2022年12月13日至2023年1月9日郑州大学附属儿童医院收治的91例Omicron变异株感染合并FS住院患儿的临床资料。根据FS类型将其分为单纯型热性惊厥(SFS)组(60例)和复杂型热性惊厥(CFS)组(31例),比较两组患儿的临床特征及实验室检查结果。结果FS症状主要表现为:双眼上翻55例(60.44%),凝视/斜视31例(34.07%),双眼紧闭5例(5.49%),意识丧失75例(82.42%),口周发绀62例(68.13%),四肢抽搐56例(61.54%),双拳紧握10例(10.99%),下肢瘫软2例(2.20%),牙关紧闭37例(40.66%),口吐白沫11例(12.09%),口周流涎8例(8.79%),呕吐(非喷射性)6例(6.59%),口角歪斜2例(2.20%),摔倒2例(2.20%),尖叫2例(2.20%),小便失禁1例(1.10%),呼吸、心跳暂停1例(1.10%)。91例患儿中,男59例(64.84%),女32例(35.16%),年龄1.58(2.33,3.58)岁,40例(58.83%)有热性惊厥史(23例热性惊厥史不详),接种疫苗68例(74.73%),1~3岁儿童52例(57.14%),62例(68.13%)1次热程仅发作1次,66例(72.53%)1次惊厥发作持续时间小于5 min。SFS组和CFS组在临床分型和疫苗接种上的差异无统计学意义(P>0.05)。白介素-10(IL-10)升高66例(72.53%),白介素-6(IL-6)升高37例(40.66%),白介素-4(IL-4)升高10例(10.99%),γ干扰素(IFN-γ)升高2例(2.20%)。SFS组和CFS组在白介素-2(IL-2)、IL-4、IL-6、IL-10、肿瘤坏死因子-α(TNF-α)、IFN-γ、白介素-17a(IL-17a)、白介素-12P70(IL-12P70)水平及升高比例上的差异无统计学意义(P>0.05)。SFS组和CFS组在白细胞(WBC)、中性粒细胞(NEU)、淋巴细胞(LYM)、单核细胞(MONO)、血小板(PLT)、C反应蛋白(CRP)、降钙素原(PCT)升高比例,钠离子(Na^(+))、氯离子(Cl^(-))、钾离子(K^(+))、钙离子(Ca^(2+))、乳酸脱氢酶(LDH)、α-羟丁酸脱氢酶(HBDH)、肌酸激酶(CK)、肌酸激酶同工酶(CK-MB)水平上的差异均无统计学意义(P>0.05)。结论Omicron变异株感染合并热性惊厥患儿,男性多于女性,发病年龄主要集中在1~3岁,热性惊厥类型主要为单纯型热性惊厥,1次热程多为1次FS发作,大多数患儿在热性惊厥发作5 min内可自行缓解。IL-2、IL-4、IL-6、IL-10、TNF-α、IFN-γ、IL-17a、IL-12P70在单纯型热性惊厥及复杂性热性惊厥儿童中的表达无差异。

母亲新型冠状病毒Omicron变异株感染的 新生儿近期临床结局

目的探讨母亲新型冠状病毒(SARS-CoV-2)Omicron变异株感染对新生儿近期临床结局的影响。方法以2022年12月8日至2023年1月8日在钦州市妇幼保健院产科收治的423例孕妇及其分娩的活产新生儿为研究对象,根据孕妇是否确诊新型SARS-CoV-2 Omicron变异株感染,分为SARS-CoV-2阳性组和SARS-CoV-2阴性组,分析孕妇感染Omicron变异株的临床特征,比较两组母亲和新生儿近期临床结局。结果研究期间共收治的423例孕妇中,SARS-CoV-2 Omicron变异株感染者133例,未感染者290例;双胎妊娠6例,单胎妊娠417例,有症状感染者占多数(92例,69.2%),均为轻型,常见症状为发热(71例,53.4%)、咳嗽(45例,33.8%)。SARS-CoV-2阳性组胎儿窘迫、剖宫产发生率高于SARS-CoV-2阴性组(23.7%vs.10.5%、52.6%vs.42.1%,χ^(2)=12.788、4.104,P<0.05)。两组孕妇妊娠年龄、住院天数、妊娠期糖尿病、妊娠期高血压、胎膜早破情况的差异无统计学意义(P>0.05)。与SARS-CoV-2阴性组相比,SARS-CoV-2阳性组新生儿生后需收治新生儿病房治疗的比例明显增高(37.8%vs.25.5%,χ^(2)=6.712,P<0.05)。两组新生儿早产、低出生体重儿、小于胎龄儿、新生儿呼吸窘迫综合征(RDS)发生率差异均无统计学意义(P>0.05)。两组需要氧疗、无创呼吸支持、有创呼吸支持的比例差异无统计学意义(P>0.05)。结论妊娠晚期感染新型冠状病毒Omicron变异株孕妇以轻型为主,常见症状为发热、咳嗽。SARS-CoV-2阳性母亲胎儿窘迫、剖宫产比例增加,分娩的新生儿收治新生儿病房比例增加,但这部分新生儿未出现与新型冠状病毒相关的临床症状或并发症,且近期结局良好。

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.

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.

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.

Clinical and immunological features of convalescent pediatric patients infected with the SARS-CoV-2 Omicron variant in Tianjin, China

COVID-19 has spread surprisingly fast worldwide, and new variants continue to emerge. Recently, the World Health Organization acknowledged a new mutant strain “Omicron”, with children were accounting for a growing share of COVID-19 cases compared with other mutant strains. However, the clinical and immunological characteristics of convalescent pediatric patients after Omicron infection were lacking. In this study, we comparatively analyzed the clinical data from pediatric patients with adult patients or healthy children and the effects of SARSCoV-2 vaccine on the clinical and immune characteristics in convalescent pediatric patients. Our results indicated that convalescent pediatric patients had unique clinical and immune characteristics different from those of adult patients or healthy children, and SARS-CoV-2 vaccination significantly affected on the clinical and immune characteristics and the prevention of nucleic acid re-detectable positive(RP) in convalescent patients. Our study further deepens the understanding of the impact of Omicron on the long-term health of pediatric patients and provides a valuable reference for the prevention and treatment of children infected with Omicron.

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.

Clinical practice of rapid antigen tests for SARS-CoV-2 Omicron variant:A single-center study in China

Responding to the fast-spreading SARS-CoV-2 Omicron variant, to improve screening efficiency, rapid antigen tests(RATs) were first added as a supplementary detection method in China in mid-March, 2022. What and how big a role RATs should play need to be supported by clinical data. Here, RAT performance and relevant factors in comparison with nucleic acid amplification tests(NAATs) were assessed in Omicron-infected inpatients. From the NAAT results, nasopharyngeal swabs(NPs) performed better than oropharyngeal swabs(OPs). RATs tested on NAAT positive NPs performed better than those with OP-positive samples. The RAT positivity rate was strongly associated with high levels of N and OFR1ab genes, especially in NPs where patients also had significantly longer hospital stays and shorter days from symptom onset to RAT testing. Self-performed RATs had a detection accuracy that was comparable to professionally performed RATs when the subjects were well guided. The antigen negative rate of the studied patients was 100% at discharge. These findings suggest that, in addition to a supplementary detection role, RATs can be an important strategy for evaluating the disease progression of Omicron-infected inpatients. This study provides important clinical data to support better rules regarding RATs under China’s COVID-19 prevention and control policy.

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.

Sanger Sequencing for Molecular Diagnosis of SARS-CoV-2 Omicron Subvariants and Its Challenges

Large population passages of the SARS-CoV-2 in the past two and a half years have allowed the circulating virus to accumulate an increasing number of mutations in its genome. The most recently emerging Omicron subvariants have the highest number of mutations in the Spike (S) protein gene and these mutations mainly occur in the receptor-binding domain (RBD) and the N-terminal domain (NTD) of the S gene. The European Centre for Disease Prevention and Control (eCDC) and the World Health Organization (WHO) recommend partial Sanger sequencing of the SARS-CoV-2 S gene RBD and NTD on the polymerase chain reaction (PCR)-positive samples in diagnostic laboratories as a practical means of determining the variants of concern to monitor possible increased transmissibility, increased virulence, or reduced effectiveness of vaccines against them. The author’s diagnostic laboratory has implemented the eCDC/WHO recommendation by sequencing a 398-base segment of the N gene for the definitive detection of SARS-CoV-2 in clinical samples, and sequencing a 445-base segment of the RBD and a 490 - 509-base segment of the NTD for variant determination. This paper presents 5 selective cases to illustrate the challenges of using Sanger sequencing to diagnose Omicron subvariants when the samples harbor a high level of co-existing minor subvariant sequences with multi-allelic single nucleotide polymorphisms (SNPs) or possible recombinant Omicron subvariants containing a BA.2 RBD and an atypical BA.1 NTD, which can only be detected by using specially designed PCR primers. In addition, Sanger sequencing may reveal unclassified subvariants, such as BA.4/BA.5 with L84I mutation in the S gene NTD. The current large-scale surveillance programs using next-generation sequencing (NGS) do not face similar problems because NGS focuses on deriving consensus sequence.

The latest research progress of novel coronavirus "Omicron sub-variant BA.5"

Since the outbreak of COVID-19,severe acute respiratory syndrome coronavirus 2 genome is still mutating,forming a variety of variants with strong transmission capacity,causing the spread of the epidemic worldwide,posing a serious threat to people's physical and mental health,and posing a major challenge to global public health.Omicron remains the main variant in several outbreaks worldwide,accounting for about 99%of the global genetic sequence.Recently,the World Health Organization announced that the subvariant of Omicron BA.5 has been found in more than 100 countries and regions around the world,causing the global epidemic rebound.However,there are few studies on the subvariant BA.5.This article reviews the latest research progress in epidemiology,infectivity,pathogenicity,vaccine and monoclonal antibody protection against Omicron subvariant BA.5,in order to provide reference for scientific prevention and control of Omicron subvariant BA.5.

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.