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1 11月22日_感染无害冠状病毒可增强针对SARS-CoV-2的免疫力 2021-11-27

Medicalxpress网站11月22日消息,苏黎世大学(UZH)的研究人员发现接触无害冠状病毒可增强针对SARS-CoV-2的免疫力。研究人员检测了在SARS-CoV-2出现之前采集的825份血清样本对其他四种人类冠状病毒的抗体水平。研究人员还检测了来自SARS-CoV-2感染者的389份血清样本,并将这些分析结果与基于计算机的模型相结合,进而准确预测抗体与入侵病毒的结合和中和程度。 研究人员发现,与未感染SARS-CoV-2的人相比,SARS-CoV-2感染者体内针对引起普通感冒的冠状病毒的抗体水平较低。此外,体内有较多针对无害冠状病毒的抗体的人在感染SARS-CoV-2后住院的可能性较小。研究表明,对其他人类冠状病毒的强烈抗体反应会增加针对SARS-CoV-2的抗体水平。因此,对无害冠状病毒具有免疫力的人也能更好地抵御严重的SARS-CoV-2感染。此类免疫反应被称为交叉反应,其发生在T细胞反应中。 从感染中康复或接种疫苗后没多久的人能完全抵御SARS-CoV-2。这是因为其体内的抗体水平仍然很高。体内抗体水平会随着时间的推移而下降,不再能预防SARS-CoV-2感染,但免疫记忆会迅速重新激活身体的防御能力,刺激T细胞和抗体产生,进而产生防御能力。由记忆细胞产生的针对SARS-CoV-2的免疫反应远比交叉反应有效。但交叉免疫反应仍可以缩短感染时间并减轻感染的严重性。这与接种疫苗所实现的效果相当,只是效率更高。 尚不清楚这种交叉反应是否也有反作用。例如,通过疫苗接种获得的对SARS-CoV-2的免疫力是否也对其他人类冠状病毒有效。 查看详细>>

来源:Medical Xpress 点击量:61

2 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:121

3 11月22日_科学家开发出一种可同时测量针对SARS-CoV-2的 T细胞和抗体反应的方法 2021-11-27

Medicalxpress网站11月22日消息,卡迪夫大学的研究人员开发了一种新的血液测试,可以测量单个血液样本中针对SARS-CoV-2的T细胞和抗体反应,这些指标可用于衡量针对SARS-CoV-2的免疫反应的强弱。该测试还可用于评估接种疫苗和先前感染所引起的免疫反应的强弱。该研究发表在期刊《免疫学》上。 COVID-19的感染率不仅高,而且在接种疫苗后仍会出现突破性感染。因而,识别有感染风险的个体,了解针对SARS-CoV-2的免疫反应的具体过程非常重要。 在这项研究中,有68名参与者患有癌症,231名参与者为健康人。研究人员使用小块病毒肽刺激T细胞,如果个体之前感染过SARS-CoV-2(或接种过疫苗),T细胞会识别出这些肽,并产生称为细胞因子的化学物质,这些化学物质可以很容易被测量。该研究还监测了一些人在英国大规模接种COVID-19疫苗之前、期间和之后的T细胞和抗体反应的强弱。虽然需要接种两剂疫苗才能最大限度地提高T细胞对病毒的反应,但研究发现,先前感染过的个体只需要接种一剂疫苗即可获得相当的免疫反应。该测试也可识别出更有可能感染COVID-19的疫苗接种者。 研究发现,第二剂疫苗对癌症患者至关重要。接种了两剂疫苗的癌症患者体内产生的T细胞和抗体反应与未患癌症的疫苗接种者产生的T细胞和抗体反应水平相当。然而,一些癌症患者在接种疫苗三个月后,其体内的免疫反应急剧下降,这突出了监测免疫反应的重要性。研究人员表示,如果没有这类信息,就无法知道未来是否需要重复接种疫苗加强剂,哪些群体特别需要接种疫苗加强剂。研究人员将继续监测疫苗接种引起的T细胞和抗体反应是否可以预防接种者感染SARS-CoV-2变体,如Delta变体。https://medicalxpress.com/news/2021-11-blood-t-cell-antibody-response-sars-cov-.html 查看详细>>

来源:Medical Xpress 点击量:61

4 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:117

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