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新型冠狀病毒疫情系列之 17 — 限聚令

2020/4/21 — 16:47

資料圖片,來源:Visuals @ Unsplash

資料圖片,來源:Visuals @ Unsplash

香港已經連續10天沒有本地個案, 7天的確診個案維持在單位數字,但政府仍然準備延長「限聚令」至5月初。「限聚令」本身的效果成疑,執行混亂,有針對之嫌。香港的餐飲、消費等行業本身已生意不足,「限聚令」限制其收客,有點荒謬。政府只願意取消,“餐飲處…不得超過該處所通常座位數目的50%”的規定是偽善。(註1) 對政府高層和醫學權威來說,它只是一項「做好過唔做」的劣政。

各國的封城或局部解封的情況有所不同,隨著西方大部份國家的疫情進入平頂和開始減緩,大部份準備部份放鬆限制國民活動。

瑞典

廣告

瑞典的確診個案,直至4月20日,為1萬4千人,死亡人數1,540。它是少有的不執行嚴格封城的國家,它只限制50人集結和不准採訪老人院。瑞典的疫情已經平頂(註2),瑞典的另類做法啟示,不嚴厲限制日常經濟活動仍然可能控制疫情。

美國

廣告

美國的疫情在目前為全球最嚴重的地方,一些州份出現反封城的抗議和引來爭議。無可否認,限制經濟活動對基層打擊最大。佐治亞州重開健身房和理髮沙龍的一些商業;田納西州提前結束原先延期至4月30日的留家令;南卡羅來納州讓以前認為非必要的企業(百貨商店,跳蚤市場,花店,書店和音樂商店)重新營業。

紐約州將以大規模的抗體測試作為局部解封的條件。紐約的做法值得香港借鏡,香港以28天內無本地感染作為放鬆「限聚令」的做法過於嚴格,缺乏科學根據。(註3)

對「限聚令」的兩點質疑理據

第一個圖表顯示一些國家在採取旅遊限制與其疫情的發展。印度是首個亞洲國家,在3月13日封關;一周後,台灣,菲律賓和馬來西亞也紛紛效仿;越南,新加坡,香港,中國,老撾,文萊和緬甸也相繼相繼禁止短期遊客。從圖表看到,有些國家的疫情上升,有些下跌。

第二個圖表顯示一些國家在採取社區限制與其疫情的發展。馬來西亞在3月18日對全民實行廣泛行動限制的第一個國家;巴基斯坦和印度也分別於3月23日和3月25日封城;新加坡從4月7日開始實施“斷路器”措施,關閉了所有不必要的企業和場所,並要求居民盡可能留在家裡;越南和菲律賓分別於2月14日和3月13日封城。從圖表看到,有些國家的疫情上升,有些下跌。(註4)

在控制疫情上,社區限制以外還有其他複雜因素,以日本為例,日本正在疫情反覆的掙扎過程。日本雖然推出嚴厲的社區限制令,它的最大問題是缺乏深切治療室服務,每十萬人口,它只有5個深切治療室床位;美國有35個;德國有30個;意大利有10個。有專家表示意大利的死亡率高達10%,而德國為1%,兩者相差的原因是深切治療的床位比率相差太遠,日本的人口比意大利更老化,因而日本的情況十分危急。(註5)

第二點質疑

二、新型冠狀病毒傳播的途徑可能十分複雜。早期的三個學術模型都在估算上嚴重出錯。其中的一個學術模型在1月17日發表,當中Matteo Chinazzi把倫敦、南韓等地的受感染風險定為0.002至0.006,但當中香港為最高,風險值為0.066,香港的風險比廣東省大一倍。(註6)

三個學術模型都估算香港是中國之後的重災區,相關的估算基礎是計算中國與各地的人流情況,以推算出多少可能帶菌者以旅遊方法散播各地,再乘以每一人可以傳播給多少人,再加上平均發病日期等因素。這些因果關係大都是線性的,但剛相反,與中國人流最密的香港,遲遲未進入嚴厲封關的香港,在二、三月期間反而只錄得單位數字。

討論

新型冠狀病毒的社區爆發似乎地域性因素很強,已有專家表示確診個案數字不及死亡人數的指標性作用重要。大量的隱性帶菌者或輕症患者未必帶來社區爆發,它有點像核爆的連鎖反應,需要足夠的中子密度才能引起核變反應。因此,是否需要傳播到一些超級帶菌者,或超級帶菌者的社區密度是重要因素,則尚未有學術討論。

但以香港的疫情發表勢和醫療資源來看,它遠比日本為好,香港的「限聚令」和限制康文活動措施並無需要。

香港最需要關注的老人院問題反而沒有人關。比利時例子是一個警號(註7)。比利時的新型冠狀病毒人均死亡率全球最高,死亡總數達到了5,683,其每一百萬人的死亡人數(4月21日)為503人,相對於英國243,美國128。比利時的死亡人數一半以上來自養老院,當中只有4%進行了病毒檢測證。比利時在4月10日對全國老人院在進行了病毒測試,測試結果發現有19%的老人院院友和12%的工作人員被檢測為陽性。

 

備註

註1

香港

本港今日連續第10日沒有本地確診個案,但據悉,本月23日「限聚令」等措施屆滿後,政府很大機會再延長措施多兩周至5月初,但戶外康樂措施有機會於本月23日後重開。身兼政府抗疫督導委員會專家顧問成員的中大醫學院呼吸系統科講座教授許樹昌表示,控制社交距離措施應待連續28日沒有本地個案,及源頭不明的爆發時放寬才屬安全

註2

瑞典

Sweden

Coronavirus Cases:14,385

Deaths:1,540

Recovered:550

Sweden says leaving businesses open might be working

In contrast to Nordic neighbours and most of Europe, Sweden has not imposed extraordinary lockdown orders.

Instead, it has called for citizens to take responsibility and follow social distancing guidelines along with stronger measures such as banning gatherings of more than 50 people and halting visits to retirement homes.

"We're on a sort of plateau," Anders Tegnell, Sweden's top state epidemiologist who designed the nation's COVID-19 strategy, told Swedish news outlet TT, Bloomberg News reported Sunday.

Karin Tegmark Wisell, head of the microbiology department at Sweden's Public Health Authority, on Friday also said the number of COVID-19 cases in the country appears to be "stabilizing," according to the report.

"The trend we have seen in recent days, with a more flat curve — where we have many new cases, but not a daily increase — is stabilizing. We are seeing the same pattern for patients in intensive care," Wisell said.

註3

Georgia, Tennessee, SC announce plans to reopen some businesses, wind down coronavirus stay-at-home orders

Georgia Gov. Brian Kemp said certain businesses, including gyms and hair salons, can reopen beginning this Friday. Meanwhile, Tennessee Gov. Bill Lee confirmed his state's stay-at-home order, previously extended to April 30, will end that day. And, South Carolina Gov. Henry McMaster said businesses previously deemed nonessential -- department stores, flea markets, florists, bookstores and music shops -- could reopen their doors.

https://www.politico.com/states/new-york/albany/story/2020/04/19/cuomo-says-state-to-test-thousands-for-covid-19-antibodies-1277850

New York will begin testing thousands of residents this week for Covid-19 antibodies as the state moves to reopen the economy in the coming weeks and months, Gov. Andrew Cuomo said Sunday.

With data suggesting the coronavirus has passed its apex in New York, Cuomo said health officials will begin conducting an initial 2,000 antibody tests per day — or 14,000 a week — on a random sample of New Yorkers in addition to its diagnostic testing for the virus.

註4

https://www.straitstimes.com/multimedia/graphics/2020/04/covid19-asia-slowing-the-spread/index.html?hpbanner

註5

日本

Japan

Coronavirus Cases: 10,797

Deaths: 236

Recovered: 1,159

https://www.japantimes.co.jp/news/2020/04/18/national/coronavirus-japan-hospitals/#.Xp0xT0BuKUk

Many hospitals also lack ICUs, with only five per 100,000 people, compared with about 30 in Germany, 35 in the U.S. and 12 in Italy, said Osamu Nishida, head of the Japanese Society of Intensive Care Medicine.

Italy’s 10 percent mortality rate, versus Germany’s 1 percent, is partly due to the shortage of ICU facilities, Nishida said.

“Japan, with ICUs not even half of Italy’s, is expected to face a (spike in fatalities) very quickly,” he said.

註6

向李文亮醫生致敬

病毒的擴散

第一個問題是病毒的擴散規模,現時基本上有三個電腦模型(Modelling)預測病毒的擴散和存在於武漢巿的總受感染人數。它們分別是香港大學公共衛生學院Professor Joseph Wu在1月31日發表的數學模型;其二(註2)是Jonathan M. Read, Jessica R.E. Bridgen, Derek A.T. Cummings,Antonia Ho, Chris P.,Jewell等人在1月24日發表的模型;其三(註3)是Matteo Chinazzi, Jessica T. Davis, Corrado Gioannini, Maria Litvinova, Ana Pastore y Pionttil, Luca Rossi,, Xinyue Xiong, M. Elizabeth Hallora, Ira M. Longini Jr., Alessandro Vespignanil 等人在1月27日發表的模型。

註7

https://www.brusselstimes.com/all-news/belgium-all-news/107068/coronavirus-belgium-tops-the-world-in-number-of-deaths-in-relation-to-population/

Today, the public health authority reported 230 deaths. Yesterday, the number was 290. That brings the total number of deaths to 5,683 since the outbreak of the coronavirus.

More than half of them have been reported from retirement homes. Of the total deaths that occurred in the homes, 4% were cases confirmed by a coronavirus test and 96% were suspected ones.

The Belgian way of reporting differs from other countries where only cases confirmed by a test are included in the statistics. However, since the authorities on 10 April started a program of testing of all residents and staff in the retirement homes, the picture about the spread of the coronavirus in the homes has started to be clearing.

The latest figures from the Belgian public health authority show that 19 % of the residents and 12 % of the staff were tested positive. On Thursday (16 April), epidemiologist Brecht Devleesschauwer from Sciensano confirmed that the excess mortality in retirement homes has been significantly increasing since mid-March and exceed the levels during the 2018 influenza season.

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