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1 Medicalxpress,11月22日,Population impact of SARS-CoV-2 variants with enhanced transmissibility and/or partial immune escape 2021-11-27

SARS-CoV-2 variants of concern exhibit varying degrees of transmissibility and,in some cases,escape from acquired immunity.Much effort has been devoted to measuring these phenotypes,but understanding their impact on the course of the pandemic–especially that of immune escape–has remained achallenge.Here,we use amathematical model to simulate the dynamics of wildtype and variant strains of SARS-CoV-2 in the context of vaccine rollout and nonpharmaceutical interventions.We show that variants with enhanced transmissibility frequently increase epidemic severity,whereas those with partial immune escape either fail to spread widely,or primarily cause reinfections and breakthrough infections.However,when these phenotypes are combined,a variant can continue spreading even as immunity builds up in the population,limiting the impact of vaccination and exacerbating the epidemic.These findings help explain the trajectories of past and present SARS-CoV-2 variants and may inform variant assessment and response in the future. 查看详细>>

来源:Medical Xpress 点击量:66

2 Medicalxpress,11月22日,Pfizer says COVID shot 100% effective in adolescents after 4 months 2021-11-27

Pfizer and BioNTech said Monday their COVID-19 vaccine remained 100 percent effective in children 12 to 15 years old,four months after the second dose. The companies said that the new data,which involved 2,228 trial participants,will help support their applications for full approval in the United States and worldwide. No serious safety concerns were observed in individuals with at least six months of follow-up after the second dose. "As the global health community works to increase the number of vaccinated people around the world,these additional data provide further confidence in our vaccine's safety and effectiveness profile in adolescents,"said Pfizer CEO Albert Bourla in astatement. "This is especially important as we see rates of COVID-19 climbing in this age group in some regions,while vaccine uptake has slowed.We look forward to sharing these data with the FDA and other regulators." The vaccine was granted"emergency use authorization"for adolescents by the US in May and the companies plan to soon seek full approval.The vaccine is currently only fully approved in people aged 16 and older. Among the 2,228 participants,there were 30 confirmed symptomatic COVID cases without evidence of prior infection,all in the placebo group. This corresponds to avaccine efficacy of 100 percent.Efficacy was consistently high across gender,race,obesity levels and comorbidity status. The main safety concern among this age group is vaccine-linked myocarditis(heart inflammation)in males. But such cases are very rare,and the benefits of vaccination continue to strongly outweigh the risks,data has shown.COVID itself can cause myocarditis,both more often and amore severe form. 查看详细>>

来源:Medical Xpress 点击量:66

3 Medicalxpress,11月18日,Simple, synthetic structure that mimics surface of SARS-CoV-2 mounts robust immune response in mice 2021-11-27

In aviral infection,what's the signal from the virus that alerts the immune system to produce protective neutralizing antibodies? That's abig question that scientists seek to answer when trying to understand disease or develop drugs to treat or vaccinate against COVID-19 and other viruses. "The answer to this question is not simple,"said Wei Cheng,associate professor at the University of Michigan College of Pharmacy."Most infectious viral agents identified to date are made of complex assemblies of proteins and nucleic acids,along with other constituents that are important for viral fitness and used by viruses to their advantage for replication and proliferation in the infected host." To that end,Cheng's lab developed asimple,synthetic structure that mimics the surface of SARS-CoV-2,that when injected into mice,mounted arobust protective antibody response to SARS-CoV-2,without the need of any other disease fighting agents,called adjuvants.The findings appear in the journal Bioconjugate Chemistry and were featured as an ACS Editors'Choice.Co-authors are Wei-Yun Wholey,senior staff member,and doctoral student Sekou-Tidiane Yoda. "This question of what signals an immune response is important for rational design of vaccines and also important for understanding the early events in aviral infection that could be targeted for therapeutic intervention,"Cheng said."What this result implies is that an ordered assembly of the viral entry protein is all that is needed to initiate an antiviral response.The detailed molecular mechanisms behind this phenomenon remain unclear,but this study made an interesting step forward in our understanding toward viral immunogenicity." The mimetic of the viral surface made in Cheng's lab is unable to replicate or infect,so it is much safer than working with live viruses in the lab,Cheng said.The technology uses asmall bit of the SARS-CoV-2 spike protein,called the receptor binding domain.This is the so-called"key"that when bound to receptors on our cells—the lock—starts amolecular cascade of events that allows the virus to infect the cell. Wholey and Yoda purified the protein and then"decorated"the surface of afat droplet with the material.They oriented the protein in aspecific way designed to mimic the spike surface of SARS-CoV-2.Purifying the protein is important because eliminating unnecessary materials makes it easier for scientists to identify specifically what caused the immune response,Cheng said. They then injected the protein-decorated fat droplet into mice.Even without the addition of other adjuvants,or disease-fighting agents,into the fat droplet,a robust protective antibody response was mounted. "The efficacy was very surprising,"Cheng said."What made this result interesting is that Wholey and Yoda only included one protein from the virus.The fat droplet is actually astructure that is found almost everywhere in and outside our cells." Unlike other work in the field,the Cheng team did not include other immunostimulatory molecules such as adjuvants in their experiments,the inclusion of which would make study of the causality more difficult.This also suggests that asimple ingredient could result in potent immune responses that are needed for vaccines. 查看详细>>

来源:Medical Xpress 点击量:28

4 Biospace,11月16日,Vaxart Announces Publication of Complete Data from Preclinical COVID-19 Oral Vaccine Hamster Challenge Study in Journal of Infectious Diseases 2021-11-21

About the Study The study evaluated Vaxart’s recombinant adenoviral vaccine,with doses administered at 0and 4weeks.Animals were challenged with SARS-CoV-2 at week 8.Hamsters are considered an excellent model for assessing COVID-19 infection because they can be infected via the intranasal route and,if infected,they demonstrate clinical symptoms such as weight loss,labored breathing and ruffled fur.Furthermore,images of hamsters infected with SARS-CoV-2 reveal severe lung injury comparable to what has been observed in infected human lungs,including severe,multi-lobular ground glass opacity and regions of lung inflammation. About Vaxart Vaxart is aclinical-stage biotechnology company developing arange of oral recombinant vaccines based on its proprietary delivery platform.Vaxart vaccines are designed to be administered using tablets that can be stored and shipped without refrigeration and eliminate the risk of needle-stick injury.Vaxart believes that its proprietary tablet vaccine delivery platform is suitable to deliver recombinant vaccines,positioning the company to develop oral versions of currently marketed vaccines and to design recombinant vaccines for new indications.Vaxart’s development programs currently include tablet vaccines designed to protect against coronavirus,norovirus,seasonal influenza,and respiratory syncytial virus(RSV),as well as atherapeutic vaccine for human papillomavirus(HPV),Vaxart’s first immune-oncology indication.Vaxart has filed broad domestic and international patent applications covering its proprietary technology and creations for oral vaccination using adenovirus and TLR3 agonists. Note Regarding Forward-Looking Statements This press release contains forward-looking statements that involve substantial risks and uncertainties.All statements,other than statements of historical facts,included in this press release regarding Vaxart's strategy,prospects,plans and objectives,results from pre-clinical and clinical trials,commercialization agreements and licenses,and beliefs and expectations of management are forward-looking statements.These forward-looking statements may be accompanied by such words as"should,""believe,""could,""potential,""will,""expected,""plan,"and other words and terms of similar meaning.Examples of such statements include,but are not limited to,statements relating to Vaxart's ability to develop and commercialize its product candidates,including its vaccine booster products;Vaxart's expectations regarding clinical results and trial data;and Vaxart's expectations with respect to the effectiveness of its product candidates.Vaxart may not actually achieve the plans,carry out the intentions,or meet the expectations or projections disclosed in the forward-looking statements,and you should not place undue reliance on these forward-looking statements.Actual results or events could differ materially from the plans,intentions,expectations,and projections disclosed in the forward-looking statements.Various important factors could cause actual results or events to differ materially from the forward-looking statements that Vaxart makes,including uncertainties inherent in research and development,including the ability to meet anticipated clinical endpoints,commencement,and/or completion dates for clinical trials,regulatory submission dates,regulatory approval dates,and/or launch dates,as well as the possibility of unfavorable new clinical data and further analyses of existing clinical data;the risk that clinical trial data are subject to differing interpretations and assessments by regulatory authorities;whether regulatory authorities will be satisfied with the design of and results from the clinical studies;decisions by regulatory authorities impacting labeling,manufacturing processes,and safety that could affect the availability or commercial potential of any product candidate,including the possibility that Vaxart's product candidates may not be approved by the FDA or non-U.S.regulatory authorities;that,even if approved by the FDA or non-U.S.regulatory authorities,Vaxart's product candidates may not achieve broad market acceptance;that aVaxart collaborator may not attain development and commercial milestones;that Vaxart or its partners may experience manufacturing issues and delays due to events within,or outside of,Vaxart's or its partners'control;difficulties in production,particularly in scaling up initial production,including difficulties with production costs and yields,quality control,including stability of the product candidate and quality assurance testing,shortages of qualified personnel or key raw materials,and compliance with strictly enforced federal,state,and foreign regulations;that Vaxart may not be able to obtain,maintain,and enforce necessary patent and other intellectual property protection;that Vaxart's capital resources may be inadequate;Vaxart's ability to resolve pending legal matters;Vaxart's ability to obtain sufficient capital to fund its operations on terms acceptable to Vaxart,if at all;the impact of government healthcare proposals and policies;competitive factors;and other risks described in the"Risk Factors"sections of Vaxart's Quarterly and Annual Reports filed with the SEC.Vaxart does not assume any obligation to update any forward-looking statements,except as required by law. 查看详细>>

来源:BioSpace 点击量:29