BMJ:英国开始两种候选疫苗都对老年人有效

2021-05-15 MedSci原创 MedSci原创

英国最初两种候选疫苗都对老年人有效

在人类宿主中,SARS-CoV-2的传播遵循了异常波动和似乎不可预测的模式,这往往是由统计上的极端情况(如超级传播事件)驱动的。这些感染驱动因素从家庭到地方,再到社区活动和其他活动,在这些活动中,多条感染链合并成具有本次大流行特征的区域和高度不稳定的流行浪潮。

这种波动在空间和时间上都有波动,很难预测,而且在很大程度上独立于过去SARS-CoV-2的发病率或邻近地区的发病率。因此,在大流行开始后一年多的时间里,许多区域性疫情迅速产生了广泛的复杂遗传变异,这些变异已经开始妨碍我们对大流行过去的认识,包括明确查明其起源的努力。此外,这些不可预测的传播模式使疫苗等基本公共卫生干预措施的制定、实施和回顾性评估成为一项特别的挑战,因为观察到的短期效果可能会受到发病率随机波动的严重影响。

在这种快速变化的环境下,大规模接种疫苗已成为国际上持续和领先的抗covid-19行动。在一篇相关论文中,Lopez Bernal及其同事报告了英格兰首次大规模接种covid-19疫苗的有效性证据。疫苗接种于2020年12月8日开始,首次将核酸疫苗候选疫苗接种给英国人群——辉瑞公司基于mRNA的BNT162b2和牛津公司基于阿斯利康公司基于腺病毒DNA的ChAdOx1-S。直到2021年1月4日,辉瑞公司的疫苗才被使用,之后两种疫苗都被使用。

在最近的临床试验中,疫苗有效性衡量的是接种疫苗的人相对于未接种疫苗的对照组病例发生率的降低程度,这里根据70岁以上成年人的三种不同结果进行了估计。经标准聚合酶链反应检测确认的有症状的SARS-CoV-2感染、入院和死亡。第一次给药(BNT162b2和ChAdOx1-S)和第二次给药(仅BNT162b2)后监测结果。

在2020年12月8日至2021年2月19日的研究期间,关注VOC 202012/01(也称为B.1.1.7)的变体在英国占主导地位。在III期临床试验的令人鼓舞的结果之后,Lopez Bernal和他的同事们的数据提供了迫切需要的真实世界证据,证明疫苗对一种新的、现在普遍存在的担忧的变体有效。事实上,他们的结果表明,两种候选疫苗对有症状的SARS-CoV-2感染、住院和死亡都有显著保护作用,其有效性水平接近临床试验或其他国家的类似观察报告中已经看到的水平。

对于70岁及以上的成年人,作者报告从首次注射后28天开始,BNT162b2的疫苗有效性为61%(95%可信区间51%至69%),ChAdOx1-S的疫苗有效性为60%(41%至73%)。这两种疫苗在效果上的相似性有些出人意料,因为两种疫苗在结构上编码不同的抗原:BNT162b2包括一个双脯氨酸修饰,在结构上稳定刺突抗原并支持更强的免疫反应,而ChAdOx1-S没有。如果没有这种稳定,单是刺突蛋白可能会导致细胞异常,如合胞体(细胞融合)的形成,因此ChAdOx1-S的药物警戒性可能增加。

在80岁以上的成年人中,首次注射辉瑞的疫苗后20天内,阳性检测结果的增加可能也应该引起更多的关注。作者认为,这种风险的增加可能是由于在运动的早期阶段选择了高危个体接种疫苗。

该研究采用测试阴性设计,这意味着作者根据观察到的临床结果比较了个体的疫苗接种状况。对于有症状的SARS-CoV-2感染(该研究的主要结果),该比较以优势比给出,如果接种疫苗组和未接种疫苗组并发非SARS-CoV-2呼吸道病毒感染的发生率相同,则优势比无偏见。这种合并感染在SARS-CoV-2患者中并不罕见,未来的研究应更直接地检验上述条件是否满足,同时发生的病毒感染率并不取决于接种状况。

总的来说,Lopez Bernal及其同事的研究结果有力地支持了在英国首个covid-19疫苗接种计划的初始阶段对老年人的保护作用。然而,重要的是要强调,这两种疫苗类型仍是候选疫苗,在正在进行的确认性IV期试验期间仍在对其有效性和安全性进行评估。

原文出处

Lopez Bernal J, Andrews N, Gower C, et al. Effectiveness of the Pfizer-BioNTech and Oxford-AstraZeneca vaccines on covid-19 related symptoms, hospital admissions, and mortality in older adults in England: test negative case-control study. BMJ2021;373

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  2. [GetPortalCommentsPageByObjectIdResponse(id=1937315, encodeId=ad48193e31526, content=<a href='/topic/show?id=d6262e4688b' target=_blank style='color:#2F92EE;'>#候选疫苗#</a>, beContent=null, objectType=article, channel=null, level=null, likeNumber=24, replyNumber=0, topicName=null, topicId=null, topicList=[TopicDto(id=27468, encryptionId=d6262e4688b, topicName=候选疫苗)], attachment=null, authenticateStatus=null, createdAvatar=, createdBy=e5742500212, createdName=12498f17m66暂无昵称, createdTime=Sun Aug 29 09:20:02 CST 2021, time=2021-08-29, status=1, ipAttribution=), GetPortalCommentsPageByObjectIdResponse(id=978214, encodeId=a2d99e8214c7, content=好, beContent=null, objectType=article, channel=null, level=null, likeNumber=45, replyNumber=0, topicName=null, topicId=null, topicList=[], attachment=null, authenticateStatus=null, createdAvatar=null, createdBy=cc6d4879920, createdName=1367586, createdTime=Wed Jun 30 14:36:43 CST 2021, time=2021-06-30, status=1, ipAttribution=), GetPortalCommentsPageByObjectIdResponse(id=1849257, encodeId=672f184925e07, content=<a href='/topic/show?id=2977356edc' target=_blank style='color:#2F92EE;'>#BMJ#</a>, beContent=null, objectType=article, channel=null, level=null, likeNumber=30, replyNumber=0, topicName=null, topicId=null, topicList=[TopicDto(id=3567, encryptionId=2977356edc, topicName=BMJ)], attachment=null, authenticateStatus=null, createdAvatar=, createdBy=148754, createdName=gaoxiaoe, createdTime=Thu Feb 03 00:20:02 CST 2022, time=2022-02-03, status=1, ipAttribution=), GetPortalCommentsPageByObjectIdResponse(id=965986, encodeId=aa5e96598634, content=已读,真是受益匪浅呀。, beContent=null, objectType=article, channel=null, level=null, likeNumber=43, replyNumber=0, topicName=null, topicId=null, topicList=[], attachment=null, authenticateStatus=null, createdAvatar=null, createdBy=f03a5433387, createdName=ms5000000518166734, createdTime=Sun May 16 09:13:18 CST 2021, time=2021-05-16, status=1, ipAttribution=)]
    2021-06-30 1367586

    0

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    2022-02-03 gaoxiaoe
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    2021-05-16 ms5000000518166734

    已读,真是受益匪浅呀。

    0