香港政府發板決定購置輝瑞及科興武肺病毒疫苗,林鄭月蛾及一眾首長斷言會率先注射,以身展示疫苗的安全性。1193Please respect copyright.PENANApVx8pcH3SL
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本文章將綜合中國武肺疫苗的現況、簡介疫苗的理念,引據各方科學證據及歷史前例,對文章命題作一簡略探討。1193Please respect copyright.PENANAm63kt7slrG
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(圖1)圖中為中國Phase疫苗3臨床研究的地域分佈概覽。依據官方說法,疫苗研發之時乃為中國武肺感染人數貧乏之時,為了探討疫苗效用,中國唯有選址國外將第三期臨床實驗,其人數及地域已詳列在圖中。1193Please respect copyright.PENANA5EKBmipB56
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中國現時進入Phase3臨床研究的疫苗公司共有3間,分別為國營CNBG、科興 Sinovac及康希諾Cansino。1193Please respect copyright.PENANAUcc6laM3DA
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其中國營CNBG及科興 Sinovac生產的疫苗均為滅活病毒疫苗,而香港政府則已決定選購科興 Sinovac生產的滅活病毒疫苗,唯政府專家小組已公開向傳媒表明沒有提議政府選購中國疫苗。1193Please respect copyright.PENANAAyeDSjjwWU
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除香港外,巴西政府在9月時份用上9千萬美金向科興 Sinovac購置4千6百萬枝滅活病毒疫苗,唯香港政府現時並沒有向外公開購置金額。1193Please respect copyright.PENANALszjOtQttn
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(圖2)注射武肺疫苗的主要目的,就是誘導身體產生對抗武肺病毒的抗體。1193Please respect copyright.PENANAgU3m0V1hbu
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疫苗主要功用有三,學界現時的研究相對上側重在第一點。1193Please respect copyright.PENANAZgaC8tNqwb
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一:抗體能夠阻礙病毒進入人體細胞。1193Please respect copyright.PENANAxXgbSh32cm
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二:抗體能夠標記病毒,1193Please respect copyright.PENANAtHTahAhXiw
指示其他免疫細胞前來消滅病毒。1193Please respect copyright.PENANAiuBvgx8Los
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三:某情況下,抗體更能夠指示免疫細胞殺滅已受病毒感染的細胞。1193Please respect copyright.PENANAeNxlywpO6A
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(圖3)用二分法來界定抗體種類的話,能夠阻礙病毒進入細胞的抗體,學界稱之為Neutralization Antibody。1193Please respect copyright.PENANAgo11Azf7UC
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不能夠阻礙病毒進入細胞的抗體,學界則稱之為Non-Neutralization Antibody。1193Please respect copyright.PENANAax1FTQCjR8
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換句話說,抗體並不是越多就越好,要有足夠多數量的Neutralization Antibody才能達到防疫功效。1193Please respect copyright.PENANAcFJd9fBdBE
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(圖4)用上滅活病毒製作疫苗的話,人體產生的抗體會拼合在病毒不同位置之上。1193Please respect copyright.PENANA4NNmB39Awc
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若抗體並非拼合在S protein裡頭的關鍵位置上,產生的抗體有較大成數無法阻礙病毒進入細胞,亦即為Non-Neutralization Antibody。1193Please respect copyright.PENANAWI2M0ujcGf
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相反,其他主流疫苗用上不同方式在人體內表達武肺S protein,人體產生的抗體主力針對S protein,較大成數為Neutralization Antibody。1193Please respect copyright.PENANAuxZSkccJ9c
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(圖5)滅活病毒疫苗有較大成數會產生Non-Neutralization Antibody,那又如何呢?1193Please respect copyright.PENANAaNaDMLwWA9
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在1960年,美國利用滅活病毒製作人類呼吸道合胞病毒 (Respiratory syncytial virus)疫苗。1193Please respect copyright.PENANAPyNeL4WFvh
80%的兒童注射後出現嚴重呼吸症狀,2名兒童死亡。1193Please respect copyright.PENANA40f6LEVhT4
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事後發現,滅活病毒所製作的疫苗所產生的Non-Neutralization Antibody數量對比Neutralization Antibody為多,因此出現名為ADE的症狀,引致注射疫苗的兒童比沒有注射的兒童更容易遭受病毒侵襲以及出現嚴症。1193Please respect copyright.PENANAnMySEv5Fpm
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2016年,WHO世衛批准菲律賓為9歲以下的兒童注射以登革熱滅活病毒製作的Dengvaxia疫苗 ,認可其安全性。1193Please respect copyright.PENANAvSegndNEG6
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奈何,2017年疫苗公司發現疫苗會產生名為ADE的症狀,亦即會導致注射疫苗的人士更容易染上登革熱或出現嚴症,下令立即停止注射。1193Please respect copyright.PENANAXu4UuRE3ab
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那時候已有超過830,000兒童注射疫苗,震驚四方。1193Please respect copyright.PENANAc8wdzuSktI
2018年9月,「官方」數字為130兒童因注射疫苗而死亡,其中19人體內發現登革熱病毒,引證ADE的存在。1193Please respect copyright.PENANAG7ti4gzECp
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既然擁有1960年ADE的先例,何解50年後菲律賓會再度出現ADE慘劇呢?1193Please respect copyright.PENANAROFSJnWCxM
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其中之一的原因是,ADE無法在動物模型確實呈現,因此非常困難能夠預先作出探討。1193Please respect copyright.PENANAPz0rh8Ed2o
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現時學界共識是,Neutralization Antibody :Non-Neutralization Antibody比例越高的話,1193Please respect copyright.PENANAUphlx0XZRZ
ADE產生的機率便越低。1193Please respect copyright.PENANAsL4MImDxwD
但非常遺憾的是,亦有個別例子Neutralization Antibody 會引發ADE症狀。1193Please respect copyright.PENANA2TXhZUMWg0
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會否出現ADE症狀,只有依靠觀察人體臨床研究的結果才能得知,1193Please respect copyright.PENANAziLJEfvgoK
這亦是為何第一間踏入臨床第三期研究的Moderna其正式完整報告官方日期為2022年7月,到那時候才會有相對確實資料疫苗會否引起ADE症狀。1193Please respect copyright.PENANA6sL1kaKRFy
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現時Moderna/輝瑞Pfizer/牛津AstraZeneca的中期第三期報告,無一能夠對ADE的安全性作出探討。1193Please respect copyright.PENANANPwMcJG4RE
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根據現時資料,最壞的ADE情況,將會是注射疫苗後的7-14日產生嚴重過敏免疫反應,肺部無法正常運作窒息而死。1193Please respect copyright.PENANAVTD63DsBGm
較好的ADE情況,將為注射疫苗後更大機會染上武漢肺炎。1193Please respect copyright.PENANAJleTgPdOAX
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在此,讓我們祝褔林鄭及三萬警察在注射疫苗後會出現ADE症狀,亦懇求麵神祝褔林鄭注射疫苗後不會出現ADE症狀。1193Please respect copyright.PENANAOIyrjPGUG1
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ADE症狀延伸閱讀:https://lihkg.com/thread/2161912/page/11193Please respect copyright.PENANAxd01uEz6um
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Ref1:https://science.sciencemag.org/content/370/6522/12631193Please respect copyright.PENANAITU2RMYlF8
Ref2:https://www.nature.com/articles/nm0109-%20%20211193Please respect copyright.PENANAdncb6XIhNm
Ref3:https://jvi.asm.org/content/jvi/94/17/e01083-20.full.pdf1193Please respect copyright.PENANAYfkPip190j
Ref4:https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30843-4/fulltext1193Please respect copyright.PENANA2ic8CYpsxM
Ref5:https://www.sciencemag.org/news/2019/04/dengue-vaccine-fiasco-leads-criminal-charges-researcher-philippines1193Please respect copyright.PENANAe5dA2VcFOV