20150310

「不會排除有此可能性」


據報章報道,香港一名醫護人員在接種流感疫苗後,出現重肌無力症(myasthenia gravis)的病徵;食物及衞生局局長高永文在接受訪問時表示,沒有醫學研究證明流感疫苗會引致有關症狀,不過,他「不會排除有此可能性」。

高永文這樣回應,合理之至,任何接受過科學訓練的人都應該這樣回應。「不會排除有此可能性」是英文 "wouldn't rule out/exclude the possibility" 的直譯,也許有人會認為這不是好中文,說「有可能」便夠清楚,而且簡潔得多。然而,「有可能」是否真的可以完全表達「不會排除有此可能性」的意思?在很多語境裏都可以,但在高永文接受訪問的這個脈絡裏,答案是「不可以」。

這裏有兩個事實:

(a) 沒有醫學研究證明流感疫苗會引致重肌無力症。
(b) 沒有醫學研究證明流感疫苗不會引致重肌無力症。

雖然高永文沒有明確指出(b), 但他說的「不會排除有此可能性」,正是基於這個事實。科學研究(當然包括醫學研究)講究的是證據,不會止於指出可能性。簡言之,如果有證據支持 p,這些證據同時可以減低 ~p 的可能性;如果證據強到足以證明 p,這些證據便可以排除 ~p 的可能性。高永文說不會排除「流感疫苗會引致重肌無力症」的可能性,表達的正是「沒有證據證明流感疫苗不會引致重肌無力症」。這個證據與可能性的關係,用「有可能」三字是不足以表達的。

同理,基於(a),高永文也可以說不會排除「流感疫苗不會引致重肌無力症」的可能性。因此,高永文那句「不會排除有此可能性」根本完全沒有指出流感疫苗和重肌無力症有任何因果關係,他只是在說話中表現了科學人應有的謹慎。

順便一提,今天在臉書無意中看到香港一位著名反疫苗人士的偉論,那是對高永文「不會排除有此可能性」一語的反應:「睇下高永文點講啦,D疫苗宗教狂熱分子!搞清楚科學係咩先啦...」這個反應,只能用「笑料」來形容。高永文一句說話,竟然令此人那麼奮亢,誰才是狂熱分子,清楚不過;更可笑的是他叫人搞清楚科學是甚麼 --- 如果他明白科學如何運作,便不會對高永文那句說話如獲至寶了。

31 則留言:

  1. 應該唔係 myasthenia gravis。高永文咁講係因為疫苗同 Guillain-Barré syndrome (GBS)係有某些噯昧關係(GBS 亦是肌肉無力,但較快復元,myasthenia gravis 手尾長好多㗎)。

    In 1976 there was a small increased risk of GBS following vaccination with an influenza vaccine made to protect against a swine flu virus. The increased risk was approximately 1 additional case of GBS per 100,000 people who got the swine flu vaccine. The Institute of Medicine (IOM) conducted a thorough scientific review of this issue in 2003 and concluded that people who received the 1976 swine influenza vaccine had an increased risk for developing GBS. Scientists have multiple theories on why this increased risk may have occurred, but the exact reason for this association remains unknown.

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    1. 咪同我拗只係單一事件,以後陸陸續續見疫苗 GBS,不過因為 1976 疫苗多人打,所以 statistically 較明顕。

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    2. 陸陸續續見疫苗 GBS?邊度啊?唔好煩搵一份有認受性的文章出來!

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    3. Approximately 30% of cases are provoked by Campylobacter jejuni, which causes diarrhea. A further 10% cases are attributable to cytomegalovirus (CMV, HHV-5). Despite this, only very few people with Campylobacter or CMV infections develop Guillain-Barré syndrome (0.25–0.65 per 1000 and 0.6–2.2 per 1000 episodes, respectively).[1] The strain of Campylobacter involved may determine the risk of GBS; different forms of the bacteria have different lipopolysaccharides on their surface, and some may induce illness (see below) while others will not.

      Links between other infections and GBS are less certain. Two other herpesviruses (Epstein–Barr virus/HHV-4 and varicella zoster virus/HHV-3) and the bacterium Mycoplasma pneumoniae have been associated with GBS.The tropical viral infection dengue fever has been associated with episodes of GBS. Previous hepatitis E virus infection has been found to be more common in people with Guillain-Barré syndrome.

      Some cases may be triggered by the influenza virus and potentially influenza vaccine. An increased incidence of Guillain–Barré syndrome followed influenza immunization that followed the 1976 swine flu outbreak (H1N1 A/NJ/76); 8.8 cases per million recipients developed the complication. Since then, close monitoring of cases attributable to vaccination has demonstrated that influenza itself can induce GBS. Small increases in incidence have been observed in subsequent vaccination campaigns, but not to the same extent.The 2009 flu pandemic vaccine (against pandemic swine flu virus H1N1/PDM09) did not cause a significant increase in cases.The benefits from vaccination to prevent influenza outweigh the small risks of GBS after vaccination. Even those who have previously experienced Guillain-Barré syndrome are considered safe to receive the vaccine in the future. Other vaccines, such as those against poliomyelitis, tetanus or measles, have not been associated with a risk of GBS.

      你到底知唔咩係GBS啊,小朋友?

      你咁講法抗生素都可以唔好用,反正某些會抗生素過敏起致死亡!

      再不如任何有副作用的藥物都唔好用,好唔好?

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    4. Mendel-Paul: wiki 英雄大佬呀,閣下識唔識英文呀?請重讀一次你自己 post 嘅嗰段英文。嗱,[Since then, close monitoring of cases attributable to vaccination has demonstrated that influenza itself can induce GBS. Small increases in incidence have been observed in subsequent vaccination campaigns, but not to the same extent]點解㗎?

      嗱,我提 GBS 係乜 context 呀?係解釋點解高永文要提[不排除。。。]嗰句:高永文咁講係因為疫苗同 Guillain-Barré syndrome (GBS)係有某些噯昧關係。。。我冇話 flu shots 一定會引起 GBS 所以千其咪打。

      咪淨識睇基本資料嘅 wiki ,去睇 VAERS 喇。仲有,我抄嗰段英文來源係 CDC。好,求其醒篇 JAMA 文你:

      http://jama.jamanetwork.com/article.aspx?articleid=199859

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  2. 不過高永文點解要提供不必要資料?因為記者死纏爛打?醒少少,狡猾,吖,我係話,圓滑啲吖嘛:

    記者:一名醫護人員接種流感疫苗後,在短時間內出現重肌無力症的病徵,疫苗引發病徴?
    高:目前無醫學文獻證明接種流感疫苗會引致有關症狀。
    記者:但明明發生咗喎!你意思唔關疫苗事?
    高:重肌無力症目前醫學無肯定病因。
    記者:咁即你唔排除流感疫苗或致重肌無力症?
    高:我亦唔排除流感疫苗可增強你 IQ 一倍,但目前無醫學文獻證明接種流感疫苗會增強 IQ。

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  3. 反疫苗人士以疫苗對極少部份人有不良副作用為由來否定疫苗能夠為絕大部份人起到抵禦或減低受到嚴重甚至致命傳染病感染的事實,其本身就已經是搞不清楚科學是甚麼。

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    1. 你不明重點:打不打疫苗乃個人決定,你不能因為我不信疫苗而以科學之名強迫我打。美國現有的爭議只因涉兒童,所以爭論在父母替兒女選擇了未必對其有利之健康決定。我打不打疫苗的個人決定,輪到你來評論?全球現在還未有急切危害全人類之疫症,可付予政府強制疫苗接種之權力。而 flu shots 不是神針,老弱年幼是打比較好,其餘的自行評估無可厚非。

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    2. 你要做賊都係你「個人決定」,「你不能因為我不信」會被人拉到而以犯罪之名強迫我唔做,之不過你做完之後。。。。

      //全球現在還未有急切危害全人類之疫症,......// 所以你要等到「全球現在有急切危害全人類之疫症」時,甚至仲要等埋確實係死咗好多人先都未遲?

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    3. //而 flu shots 不是神針,.....// 唔通係要「神針」先打?咁你就乜針都唔洗打喇...
      連醫生都唔係「神醫」,有病都唔好去睇醫生..

      你啲「理由」真係好「明重點」啊..

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    4. 各位匿名疫苗戰士:

      即係咁,all vaccines are not created equal。Core vaccines 成効高係因為 strain specific。。。flu shots 年年係靠估嚟 match 㗎,而且 flu shots 係絕對,呢世唔使諗,100% 無可能,ever,做到 herd immunity。。。mismatched vaccines 可能(可能咋)令你有較輕病徵但你一樣會受感染一樣會傳染病菌,不如一感染就鎖你一星期好唔好?點解?因為我嘅健康大晒囉!唓!

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  4. 某些人還以為接疫苗係個人決定仲痴晒線咁自己覆自己
    連herd immunity都未識就唔好出黎獻醜啦
    接疫苗除左保護自己仲有最大功用係防止傳播呀

    我諗好多人都係見到有痴線佬係咁洗版所以都廢事留言

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  5. 首先,我個人贊成要所有兒童廣泛地接受傳統疫苗注射(core vaccines:MMRV, DTaP-Hib, polio),因為此等病傳染性高,而其疫苗都有長時間安全性及有效性之驗證。此舉已成立大部分 air-borne 傳染病之 herd immunity。

    既然童年時已接受 core vaccination ,成年後再接種其他疫苗呢,我是[提倡要分清楚 medical necessity v practical necessity]之支持者。Not all vaccines are created equal,疫苗不同製法各有潛在出錯風險,所以美國另設 VICP 而禁止以 civil tort suit 向藥廠索償,但我不討論此科學層面。我要拗的是成年人對自己身體的自主權,而我認為只有在 medical necessity (各位自己 google [Harvard Law Review Towards a twenty first century Jacobson v. Massachusetts]看定義)情況下才可逾越此 civil liberty。而美國自 1905 年後就沒強制國民打任何疫苗(但實際上以入學/入政府職等來企圖強制)。

    正如墮胎的爭議,[支持墮胎者]並非真支持墮胎,而是支持婦女有身體自主權。

    洗板?哦,原來只是看 ID,不是看內容,我恍然大悟為什麼大家都是[匿名]了!

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    1. 好吧,既然你都改口話只係針對non-medical necessary 的疫苗咁當然冇人會反對你,我都冇咩好講了
      因為好多anti-vaccine支持者就係D細路因為herd immunity先冇事就以為疫苗多餘

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  6. 其實你們的爭拗根本是不必要﹕

    > 打不打疫苗乃個人決定,你不能因為我不信疫苗而以科學之名強迫我打。
    > 我個人贊成要所有兒童廣泛地接受傳統疫苗注射...我要拗的是成年人對自己身體的自主權

    爭拗的起源是第一句,因為這句其實就是反疫苗者的主張,他們主張的正是所有疫苗都不應該打,父母有權拒絕子女接種任何疫苗。

    第二句是「澄清」,如果你只是說「成年人」是否接種,則現在根本在絕大部分國家的絕大部分職業中,都不會強制接種疫苗。(就算有強制的都只是指定種類)

    現在的流感和肺炎鏈球菌疫苗,都是自願接種,政府只是資助而已。那有甚麼好拗﹖

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    1. 咁標題係關於 flu shots 吖嘛,而反疫苗者未必個個有細路,我就唔會乜疫苗都打,即使有 outbreak,所以某情況下我都可算[反疫苗者]。我個人決定關你(指閒人)事?你邊位呀?你嘅健康重要過我健康?大把人長期高鈉高脂高糖飲食+冇運動+煙酒等積弊成病拖累公眾資源,我叫政府整份飲食運動指標強迫你做得唔得?唓!

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    2. 例如某疫苗有 GBS 嘅約數係十萬人中一個,我唔鍾意個 odd 得唔得?中咗獎點算?我身強力壯寧願搏就算患流感都會自己痊癒得唔得?想以科學之名逾越人權?仲要係半桶水之所謂科學。。。

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    3. Horai,

      //我身強力壯寧願搏就算患流感都會自己痊癒得唔得?......//

      你身強力壯係咪就等於兒童或老年人都身強力壯先?
      你身強力壯可以去搏死係咪就等於身不強力不壯嘅兒童或老年人都同樣可以去搏命呢?

      如果你係想借不要「以科學之名逾越人權」嚟去令到嗰啲身不強力不壯嘅兒童或老年人去搏命,你咁做又算唔算係「黑心」先?

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    4. 全香港(其實係全球)每一流感季都有成千過萬患流感嘅番工上堂周街走散播病菌拉哂佢哋強制隔離十四日好冇?點解唔得?你親人傷風感冒仲出街就狼心狗肺係嘛?唓!

      明知現實仲專登搵嚟拗!

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    5. 唔係得唔得嘅問題,其實今年因為世衛估錯疫苗結果就出現流感比以往嚴重和死於流感嘅人多咗也可間接證明疫苗嘅重要性。

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    6. 各位 vaccine nazi :

      拗點唔係流感疫苗冇用,係打唔打個人風險自度,你打我又冇阻你冇勸你咪制,但人哋選擇唔打你班 vaccine nazi 就咪成副挾科學賴大仁大義嘅嘴面,呸!

      好,嗱,你班 nazi 認為唔打疫苗係危害社會健康嘅人渣,我雖然唔認同,但就都當你有 point,咁你父母兄弟姊妹姨媽姑姐有傷風感冒又冇禁足屋企起碼七日唔出街嘅,你就要認同佢哋亦係危害社會健康嘅人渣。。。deal?咩呀,嚴人寬己呀?

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    7. 咁標題係關於 flu shots 吖嘛——個問題係呢度根本冇人要求強制你打流感疫苗,人地贊成強制既係其他你都贊成細路要打果堆呀嘛,咁仲要嘈乜野﹖邊個納粹要迫你打唔該講明勒。

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    8. 明明冇爭議既野都混淆拗一餐,做人係咪時間多餘到咁呢﹖

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    9. 各位匿名戰士:[冇人要求強制打流感疫苗呀!]聽清楚睇清楚未?嘈乜嘈,大人鬧啦。

      但方大人,如果有人鬧,吖我係話,玩[唔講明就可以賴]遊戲,暗示唔打流感疫苗者係社會敗類呢?係我小人之心多疑?因為冇人會蠢成咁霸道成咁白痴成咁?言之有理。方大人果然睿智之人。

      方大人關心我時間太多不懂善用?例如不應花在無聊口舌之爭掃你雅興?但[看不看]好像權在你手?我又不是[匿名],累你看了才知中計。

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  7. 打與唔打嘅後果:

    http://www.guokr.com/article/437153/

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  8. 科學半桶水嘅 vaccine nazi :

    During years when the flu vaccine is not well matched to circulating viruses, it’s possible that no benefit from flu vaccination may be observed. During years when there is a good match between the flu vaccine and circulating viruses, it’s possible to measure substantial benefits from vaccination in terms of preventing flu illness. However, even during years when the vaccine match is very good, the benefits of vaccination will vary across the population, depending on characteristics of the person being vaccinated and even, potentially, which vaccine was used. ~~~~~ CDC

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    1. 你又算唔算係「科學半桶水」呀?

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    2. 你只抽取 CDC "Vaccine Effectiveness - How Well Does the Flu Vaccine Work?" 整篇文章一少部份,令人產生 CDC 都是反疫苗的印象。 其實那篇文章有好幾段是談及疫苗的好處,並且,文章的結尾如下:

      Do recent vaccine effectiveness study results support flu vaccination?

      The large numbers of flu-associated illnesses and deaths in the United States, combined with the evidence from many studies showing that flu vaccines help to provide protection, support the current U.S. flu vaccination recommendations. It’s important to note, however, that how well flu vaccines work will continue to vary each year, depending especially on the match between the flu vaccine and the flu viruses that are spreading and causing illness in the community, as well as the characteristics of the person being vaccinated.

      http://www.cdc.gov/flu/about/qa/vaccineeffect.htm

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    3. 喂,你意思我應該抄哂 CDC 成版以防你誤會?哦。成版幾千字喎。。。都一定要抄哂?哦。但我抄個段我無加註釋喎。。。唔得因為讀者會自行誤會?咩話,我要預知讀者會點誤會?哦。但我扭曲咗邊字邊句?乜話,成段都係扭曲 CDC 意思?但我冇改字喎。。。都係大罪?哦。

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    4. 各位 vaccine nazi,單憑我冇刪除[During years when there is a good match between the flu vaccine and circulating viruses, it’s possible to measure substantial benefits from vaccination in terms of preventing flu illnes.]呢句可唔可以從輕發落免我寫十萬字嘅悔過書?

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  9. 如果接種某疫苗有少許機會出現副作用,但要有一定接種率才能達到人群疫苗,咁最理想情況係除自己以外人人接種。自己不用承擔接種副作用的風險,也不會有人傳染給自己。

    可是人人有這心態就不能達到人群疫苗的接種率。Prisoner's dilemma?

    Sirius

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