無可避免的抗疫終點站

九個月前寫下的 Blog 有以下的猜想：

“... ... 倘若 Omicron 在內地爆發，相信中央政府亦難敵經濟滑落的壓力或民眾的極端反應，恐怕也要放棄「動態清零」了，推出「中國式共存」新口號，例如先把新冠病毒歸類為甚麼新感冒，到時候港府官員及一眾忠心耿耿的良好市民也定必出來擁護「中國香港式共存」！把話說得太盡，不留轉身餘地，實在不智。明明說好要「堅持清零」到底，不負中央心意，突然轉軚又情何以堪？明明說過與病毒共存就必共赴黃泉，但倘若中央一聲令下，又馬上毫不動搖的去配合黃泉之路。說得過去嗎？” --- 2022年3月

現在基本上可以說是應驗了。事實上，基於科學數據和觀察先進國家於2022年初開始對抗疫政策的轉向，也不難估計所謂「共存」將是全球唯一合理的抗疫終點站。

沒想到的是內地的180度轉向，毫無準備的撤銷幾乎所有的防疫措施，各城市海嘯式爆發的消息不斷傳出，由於官方行事欠缺透明度，外界無法得知中國疫情的實質情況，加上在大規模的爆發下，有鑑於去年印度的 Delta 病毒株，病毒變種確實存在一些不確定性。歷史重回到2020年初武漢的情況，各國紛紛從新向中、港、澳人士作出入境限制，如從新要求提供PCR陰性證明方可入境等措施，對蠢蠢欲動的港人做成嚴重打擊！樂觀的看，現在大部份地區包括香港的疫苗接種率已達至足夠建立免疫屏障，即使再爆發理應比2020年的輕微。

可憐的香港政府，全無自主能力，一班醫學精英只能被動應對。中央說要毫不動搖的清零，局長也毫不動搖的追隨，在年初至今 Omicron 流行的感染數據和病徵已廣受理解的背景下，仍然發表黃泉偉論。如今中央說要與「新冠感染」共存（正確的說法是「新冠肺炎」已經成功清零了）， 局長也毫不動搖的追隨，需有點兒尷尬，仍然理直氣壯的撤銷幾乎所有防疫措施。港府官員過去數個月的表現，證明只需緊緊追隨中央的路線，絕對忠誠，已經功德圓滿了。

但某某重要人物又好像曾經說過「忠誠廢物」也不為中央所欲！所以說，當官難就難在如何精準揣摩上意。不論你的能力有多高，想法有多好，不符中央心意也只是自作聰明。但只懂盲跟中央，做其應聲蟲，亦恐被指為一件忠誠廢物，難逃最終被棄置的宿命！

2022年12月29日

Japan tops the most likeable country list!

Since Japan reopened to foreign visitors, it has been on the top of the priority list for the starved tourists all over Asia. Over 90% of Hong Kong people have put Japanese cities as their first and preferred destinations. The likeableness of Japan is self-evident, as thousands have rushed to pack their luggage for a Japanese holiday since October. Tokyo, Osaka, Kyoto, Nagoya, Sapporo, Fukuoka, ..., are all on the booking list. Airlines have been resuming flights to Japanese cities as first-tier destinations, amidst the slowly recovering flight capacity. Other Asian cities apparently don't get a proportionate share! 

As a post-pandemic observation, countries having this level of charm do reflect a cultural strength and soft power that took years to build. The variety of attractions Japan offers is amazing, from beef rice bowls to fine omakase dining, concert halls to vinyl cafes, designer brands to vintage, city walk to natural scenic hike, homestay to hot spring resorts, and general to subcultural interests, all representing a very unique destination for visitors with different interests. More importantly, Japanese society is generally admired by visitors for being polite, patient, friendly, fair, and subtly sophisticated. The many small details, which people could hardly recall one by one, have added up to make people feel the comfort and peace of mind, including the friendly facilities, the aestheticity of Japanese design, advanced yet subtle technology, clean and calm environment, the feeling of safety, etc. You don't get to see people shout in subways or dance with noisy loudspeaker music in parks or public squares!

It's interesting to probe a bit into what makes a country so likeable, or on the contrary so unlikeable! After the three years of the pandemic, we clearly see the differences and find part of the answers being rooted in the way a country is run, how people are educated and what values they hold. 

December 28, 2022

It's time to make a turn!

中國實行了接近三年針對新冠疫情的「清零」防控政策，西方國家望塵莫及，更無法想像中國如何能長期實施封省、封城、封區、天天檢測核酸、限制出入自由的同時，大多數老百姓又彷彿心甘情願配合政府的抗疫政策，相信國家為了保障人民健康，毫不動搖的堅持「清零」政策，並對國家心存感激！如此順民，神州以外，天下難尋！

要解構中國的「清零」創舉，必先理解政府長久以來為社會創造的基本條件，其中關鍵之一在於控制資訊的內容和流通。中國之所以能體現和諧社會，全憑對資訊的全面規劃和高度監控。想像一下，如果你所接收的唯一資訊，把感染新冠說成世上最可怕的絕症，一旦感染了新冠病毒，就必死無疑，算是僥倖避過死神，也只剩半條人命，將來的生活還可能面對其他人的歧視；那麼，你也許都會毫不懷疑的配合當局的防疫政策，直至當局宣布抗疫成功，解除所有防疫措施。如果你知道西方國家已經開放，恢復正常生活的話，告訴你他們是「躺平」，是不負責任的政府，你更要加倍感恩在中國受到保護。而事實上，從2020年初開始，新冠病毒的主導病毒株的演變從 alpha、beta、gamma，一直到2022年初的 omicron，感染力增強，但同時殺傷力減弱，與流感相比，已無多大區別。西方國家的先進疫苗和高接種率的事實，更不跟你說！科學一點，誰說流感不會死人？誰說流感不會導致嚴重後遺症？誰說流感不會對醫療系統做成嚴重影響？每年的流感高峰期，為何不封省、封城、封區？ 

問題是，若抗疫路線同時是政治路線的展現，一旦政治狀況有所改變，抗疫路線有調整餘地的時候，如何把劇本改編，令人民從新接受新冠病毒其實並不可怕，大家可以放心，似乎也有一定難度。新冠病毒演變成風土病的趨勢，相信無可避免，劇本終需改寫，大家可以拭目以待！

局長以及一眾高官為表忠誠，政治先行，發表愚蠢及違背科學的言論，並堅持不合時宜的抗疫政策。倘若中央的抗疫政策有所改變（基於外國經驗和科學分析，與病毒共存是必然的路），不再堅持清零的話，相信最難堪的莫過於這群精英們，大家可以翹埋雙手看他們的面皮有多厚！

2022年11月15日

How likely you have a friend already infected with Omicron if you live in Hong Kong?

The official infected number in the fifth wave of Covid in Hong Kong so far is around 1.2 million, out of the total population of 7.5 million. So, 16% of our population have got infected with Omicron, and 84% not yet infected. This means the probability that any particular person in Hong Kong has got infected is 0.16. Let's assume this is the case.

Suppose you have N friends. The question is how likely at least one of your friends is among the 1.2 million. A shortcut to finding the answer is to first consider the complementary question of how likely none of your friends has got infected, and that's simply 0.84^N.

The complement of this probability is exactly the probability of having at least one of your friends infected, which is 1 – 0.84^N.

So, if you have 10 friends, i.e., N = 10, you have 82.5% chance of having at least one of your friends infected. If you have 20 friends, it's 96.94% chance, and if you have 40 friends, 99.9%. On average, each person has around 150 contacts on her or his phone book, according to Dunbar's number. That means the chance is 1.

April 24, 2022

Hair Salons — Subtly Indispensable! 原來飛髮舖係咁重要！

Have you ever thought seriously about what has been truly indispensable to you?

The two-year-long pandemic has trained people to tolerate the absence of facilities that used to be considered essential or to find alternatives to the activities they used to enjoy. Most people have now got used to living without fitness centres, sports venues, cinemas, concert halls, and even restaurants (after 6pm), but not hair salons!   

Seeing the aggressive fifth wave of covid, Hong Kong Government panickedly added barbershops and hair salons in early February to the list of business venues that were ordered to close.  But in less than a month, the government decided to allow barbershops and hair salons to reopen, after realizing the subtle but desperate need for getting a haircut by most people!  Other businesses were jealous of such exclusive privilege to reopen. 

The importance of barbershops and hair salons has obviously been underestimated or totally unnoticed. Only until now when Government ordered their closure that people seriously felt their vitality! On the day before closure, we saw long queues of people outside almost all QB House branches rushing to get a haircut, and on the first day of reopening, we again saw long queues of people fearing possible sudden reclosure of barbershops. What a phenomenon! 

My 80-year-old father-in-law rushed to get his first jab of covid vaccine just for the sake of getting access to his favourite barbershop!   

March 23, 2022

堅持清零的困惑

過去兩星期，香港第五波疫情進入高峰期，政府起初放風決意於三月底進行全民檢測，配合極端嚴厲的隔離和社交距離措施，務求盡快找出隱形患者，切斷傳播鏈，恢復動態清零，言之鑿鑿，幾萬人被嚇得匆忙離境，當中包括香港人和在港工作的外國人。

西方發達國家對變種病毒 (Omicron) 作為主流新冠病毒的病癥和嚴重性已有一定的認識，疫苗接種已達到廣泛程度(95%)，加上感染率亦已接近飽和。根據外國數據，Omicron 的威脅性已跟一般流感病毒無異，雖不能令它徹底消失，但縱然與它共存也沒甚可怕。香港錄得的死亡率（至今0.7%）比其他國家多出三成以上，和內地相比更誇張得不合情理，原因可能與死亡分類的方法有關，若將Omicron與其他病因一併計算的話，死亡率必定偏高。例如，把一位癌症末期病人感染 Omicron 後死亡的個案納入計算 Omicron 的死亡率是否恰當？ 正當大部分發達國家已經重新開放，港府還堅持清零，透過親政府人士不斷宣傳清零的好處（甚至宣揚「不清零即赴黃泉」的謬論），花費巨額建造大量隔離設施為滿足全民檢測之後衍生的隔離需要。要強調的是，「清零」（如能做到的話）的好處是無庸置疑的，但鑒於變種病毒的性質、可控性及疫苗接種率的客觀因數，理性抗疫的抉擇應在乎能否平衡可行性、社會代價和經濟代價。科學點看，「清零」乃反自然之舉，幾千年來，不同病毒從動物傳人，所經過的變異，從猛烈到溫和，最終達至與人類共存，都是典型的過程。中國稱得上是科學強國，偏偏選擇反科學而行，老百姓卻無語問蒼天！

香港政府的抗疫政策明顯脫離科學現實，面對嚴重下滑的經濟，「派錢」是唯一補教方案，但依然堅持「清零」作為抗疫目標，官員還掩耳盜鈴的假定市民相信官方發放的信息，而事實上，國際資訊仍可在香港流通，大部份香港人和在港工作的外國人已掌握 Omicron 的科學數據和對不同年齡人士的風險，並在社交媒體提出各種質疑。港府在國際社會的眼中，表現得極為愚昧，反映了它徹底失去管治的自主權，將抗疫政治化，若把「動態清零」看成不可動搖的政治立場，又如何理性抗疫？如今，根據外國數據，Omicron 的重症及死亡率與流感相若，即使全港兩百多萬人曾感染 Omicron 也屬正常，真正的焦點是能否透過接種疫苗保護長者和長期病患者。

倘若 Omicron 在內地爆發，相信中央政府亦難敵經濟滑落的壓力或民眾的極端反應，恐怕也要放棄「動態清零」了，推出「中國式共存」新口號，例如先把新冠病毒歸類為甚麼新感冒，到時候港府官員及一眾忠心耿耿的良好市民也定必出來擁護「中國香港式共存」！把話說得太盡，不留轉身餘地，實在不智。明明說好要「堅持清零」到底，不負中央心意，突然轉軚又情何以堪？明明說過與病毒共存就必共赴黃泉，但倘若中央一聲令下，又馬上毫不動搖的去配合黃泉之路。說得過去嗎？

話說「金瓶梅」中的武大郎每天在市集販賣同一款燒餅，連日滯銷，其妻潘金蓮見他苦無對策，遂獻計推銷「普天同慶燒餅」，燒餅無需改良，換湯不換藥，總之改個口號，翌日果然客似雲來。武大郎不明箇中道理，潘金蓮笑指天下蠢人何其多！

2022年3月21日

An Anecdote. Zero Covid or Coexistence?

Thirty years ago I attended an international conference in a Boston hotel during a hot summer week. In an early morning lecture, a few folks arrived at the room on time, and after the lecture began, people kept coming in at different times while the speaker spoke. Latecomers weren't totally unusual on this kind of occasion though not very respectful, but the problem was the door banged shut every time a person came in. That's annoying! Two co-chairmen, one American and one Chinese, sitting at the front bench obviously noted the situation. One of them interrupted and suggested stopping latecomers, and he made that suggestion in a friendly manner. Sounded logical! After all, the lecture had got started for more than half an hour. The other guy, however, requested the conference assistant to help get the hotel staff to fix the door. The anecdote is still relevant: fixing people versus fixing the problem. 

The fundamental issue of all the discussions in the past whole year on "zero covid versus co-existence with the virus" is between restricting people's freedom to stop the spread and achieving the needed herd immunity. If you have absolute power, you can restrict people's mobility and that's the best intervention to achieve "zero covid". This could also be morally correct in the early stage when very little was known about the virus and its possible detrimental consequence, and social restriction was the only way to stop the spread. However, this didn't work for democratic countries, even for a health cause! Even Japan and Korea, where a high level of self-discipline could be expected of people, were no exception! Numbers still soared in these countries. The fundamental conflict with western values and lifestyle naturally steered mentality shift towards finding a cure instead, an effective vaccine in this situation. They did it in an unprecedented short lead-time using advanced mRNA technology. Pfizer-BioNTech, Moderna, and Johnson & Johnson have become widely available since early last year. Furthermore, by now, we have also gained a good knowledge of the virus and the extent of its effects, though through a painful process. Most countries are now reopening their borders and lifting all remaining restrictions. 

What do we do in Hong Kong? "Zero covid" is still the official stand, while we are at the same time achieving a high vaccination rate. With Omicron being the dominating variant and being much milder, does it really justify a "zero covid" policy that relies on drastic restriction of freedom? We never needed such drastic restrictions to avoid the spreading of flu or common cold, though severe or death cases were also possible. For Hong Kong, the decision for maintaining "zero covid" has become irrational and purely political, if the vaccination rate has already reached 90%. What's the point for vaccination if you still need to trace every case and identify transmission paths? The fact is that the 0.03% severe cases among the vaccinated patients are not solely covid related because they are mostly from elderly groups or with chronic or critical illnesses. This is comparable with flu that happens every year. 

Our leaders are best at creating linguistic illusions. If you cannot achieve zero covid, you claim that you are achieving "dynamic zero covid", and if you cannot declare co-existence with the virus (as it is a political crime to comply with the evil west), you may declare "co-existence in a special way". Then, as usual, after a bit of brainwashing, we will claim another remarkable victory of a "special-style" co-existence policy! 

March 6, 2022

 

Geometric progression! "Dynamic" zero infection!

"Omicron is spreading in geometric progression!"

Our government officials and health experts have kept saying this in the past few days! Do they really know what they are talking about? Obviously not! Or they only meant to exaggerate the situation to justify the implementation of more drastic measures to support our nationwide zero-covid policy. This could be good for Hong Kong, but the abuse of mathematical terms is not acceptable or truthful, coming from our top officials and medical experts. Looking at it differently, this may simply reflect how ignorant of mathematics these people are!

Geometric progression, a secondary school math concept, means a sequence of numbers successively being kept multiplied by a fixed constant, like 1, 4, 16, 64, 256, 1024, and so on. This is a very aggressive progression! Think about it! If Omicron is indeed spreading in such a progression in Hong Kong, we should be heading to tens of thousands by now. The so-called reproduction number R0, which is used by medical professionals to indicate the contagiousness of a disease, is the number of people possibly infected from a single carrier. With no refinement, direct application of this R0 could indeed end up with the conclusion of a geometric progression with the multiplying factor being R0. If R0 = 4 for Omicron, then we should expect a progression to look like 1, 4, 16, 64, 256, 1024, 4096, 16384, 65536, ... and blowing up in a short time!

(Chart added March 5)

The truth is that spreading dynamics is nothing like this, definitely not a R0 geometric progression! It is rather governed by a dynamical process, where the rate of change of the infected number is a function of the current infected number and susceptible population size, of course with a whole bunch of parameters like infection rate (how fast the virus can spread), recovery rate, and other factors such as non-pharmaceutical interventions that suppress transmission. Technically the so-called compartmental model (commonly called SIR or SEIR in epidemiology research) is a set of differential equations describing the spreading progression, and with data generating the controlling parameters, the model can accurately track the progression. In short, it is never like a geometric progression!

Hong Kong's top officials are mostly trained with a political, art or social science background. They could be extremely sensitive and careful selecting the right words when making a political announcement, but can be completely flexible or imprecise when coming to the use of mathematical jargons.

A more outrageous example of math abuse is 'dynamic zero infection' (動態清零). The term 'dynamic' refers to variation with time. 'Zero infection' is a state of having no infection. That's clear! But 'dynamic zero infection' is a self-contradictory term. None of our top officials could explain what it actually means. Even our CE said publicly that she was not in a position to explain it as she was not the initiator (literally 我唔係始作俑者！). They all knew they could not achieve zero infection, and they all knew Beijing wouldn't like to hear the truth which is 'sometimes zero, and sometimes not zero', and so adopting the term the mainland experts invented is the only politically wise choice. The same usage can be extended to anything that the government can't do or does poorly but wouldn't like to admit.

The lesson is: when you can't find a good way to lie about your failure and you still want to lie, simply say you have made a 'dynamic' success.

February 8, 2022

Who should get vaccinated first?

Vaccination no doubt creates hope for a rapid recovery of our severely impacted economy and resumption of normal life from the long painful fight against the pandemic. The questions that concern most of us are which vaccine is more effective and whether the side effects are tolerable. Moreover, of greater interest to the policymakers is who should get vaccinated first, and which order of priority would result in the shortest time to herd immunity and/or the use of minimum resources. The point is that we don't have to vaccinate the weak or more vulnerable groups in order to protect them, but rather to vaccinate the spreaders in the community and hence protect the entire community. An elderly person could safely live in her nursing home if there were no infected caretakers or visitors!

In February 2021, Hong Kong government began offering free vaccine to the more vulnerable groups, including the elderly, medical and healthcare workers, and then teachers, taxi drivers, restaurant workers, etc., the rationale being the need for protection. However, taking a more scientific approach, the entire community is actually a network of people. Each individual has his or her own contacts. Some have more and some have less. An elderly person living in a nursing home under intermediate care would typically meet with three or four people (mostly caretakers or a couple of family visitors) daily. On the other hand, a cashier working in a convenience store could be in contact with hundreds of customers per day. In terms of the likelihood of spreading the virus, people having more contacts (technically called "degree" in a network) should more likely be the key spreaders.

A more effective approach may be to classify different groups according to the statistical average of the contact links per day. For instance, a taxi driver carries an average of 300 passengers a day; a restaurant waiter serves an average of 100 patrons a day; a teacher interacts with 50 students a day; and so on. Then, if we prioritize our order of vaccinating different groups in our community according to the average contact number of the groups, we should theoretically reach the nerd immunity state much quicker.

This is a research topic worth studying!

March 22, 2021

疫苗保護率的謬誤：統計學101

昨日，明報刊登了一篇以「稱有效率五成≠半數人有效 劉澤星：科興2/3接種者受保護」為題的報導*，引述負責審核新冠疫苗的顧問委員會召集人劉澤星先生指科興疫苗能有效保護三分之二的接種者。

按明報引述科興的數據，接種人數及接受安慰劑人數各約為5000人。前者當中85人受感染，後者168人受感染。劉先生基於 85：168（大概 1：2）的比例，推出 2/3 接種者受到保護！依照劉先生的算法，5000 這個參與者數目（採樣人數）並無任何意義！ 事實上，在某個群組所錄得的感染人數是受到許多因數影響，故需要增加採樣數目才能保證統計數字的可信性。況且，85和168是兩個群組的感染數字，很難理解如何單憑這兩個感染數字來推出疫苗的保護率。正式來說，在5000+5000 = 10000名參與者中，2/3感染者是沒有接種疫苗的。劉先生反過來說成 2/3接種者受到保護，肯定不正確。再加上，如果採樣數目不是5000，而是100萬的話，85和168、甚至1000的感染人數基本上沒有太大區別。從統計學角度看，採樣數目是非常重要的參數，絕對不能忽略。

按基本數學邏輯，5000名接種者當中有 4915人未受感染，而5000名接受安慰劑的人士當中有 4832人未受感染，這也並不代表疫苗在接種者身上可提供 4915/5000 = 98.3% 的保護率，因為接受安慰劑的也有4832/5000 = 96.64%不受感染。我們只可以估算疫苗“相對”的保護率大概為50.43% （科興的50.66%應該是基於更準確的數字和統計方案）。

劉先生的2/3保護比例的說法有誤導公眾之嫌，必須予以修正。

2021年2月19日

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*「稱有效率五成≠半數人有效 劉澤星：科興2/3接種者受保護」— 明報 2020年2月18日

問題翻譯 2.0

香港政府推出「抗疫基金」，為受COVID影響的企業和市民提供援助，「抗疫基金」英文竟然直譯為「Anti-Epidemic Fund」。不懂中文的朋友起初以為是為醫護界提供額外資源，務求儘快遏止病毒蔓延，又或者是為香港生物科技業界提供資金，加速研製疫苗。但香港並無研發疫苗的機構，大學也只是與某些內地和海外研究團隊合作而已，何來Anti-Epidemic 的 Fund？

Anti-Epidemic 明顯是「抗-疫」的直譯， 先有中，後譯英。問題是，有關政策局和行政部門精英雲集，竟無人察覺，讓如此垃圾翻譯出街，非常搞笑！美國類似基金叫「COVID-19 Relief Fund」，語義非常清晰，字眼是 relief，目標自然是為紓緩市民大眾因疫情所遭受的經濟困境而提供的援助。除了Anti-Epidemic 本身的意譯誤差，執行翻譯的官員的基本事實查證也欠妥，世衛在港府推出「抗疫基金」之前已老早宣布 COVID-19 成為全球大流行，本來的 Epidemic 已升級為 Pandemic，就算是誤譯也應該是 Anti-Pandemic Fund 才錯得對，現在乃錯上錯！

幾年前寫過兩篇關於香港的問題翻譯的博文1,2，主要是中譯的問題，是先英後中所牽涉的技術問題和文化差異產生的誤譯。現在剛剛相反，進化為問題翻譯 2.0！

2020年10月19日

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1 博士候選人：你幾時去參選？
2 從航機廣播看中國人的自信

政府能否洞悉全民檢測的信息？

自新冠肺炎疫情爆發以來，香港政府一直忽視科學防控，檢測率偏低，疫情一波接一波的出現，一波比一波的嚴重。

最需要增強檢測率的是每一波疫情的早、中期，大量檢測可以及早找出隱形帶菌者引起的傳播暗鏈，這是有科學依據的。但當確診數目降至單位數字，隱形帶菌者比例亦已大幅下降，明顯已經錯失了全民檢測的最佳時機。政府卻排除專業意見，一廂情願預算幾百萬人會接受檢測，揚言能找出1500隱形患者。最新數字顯示，從106萬的已檢測案例中，只找到16個懷疑隱形患者，即一百萬分之十五（0.0015%)。

「全民自願檢測計畫」在效益最低之際推出，令人莫名其妙！被傳媒追問所需成本時，政府避而不談，只強調是獲中央幫助，有常識的都知道乃天文數字**！令市民大為反感的是全民檢測在各區設立檢測站，操作方式實際上與立法會選舉無異。政府以疫情為由，提早宣布取消9月初的選舉，不予任何討論餘地，明顯是為要部署改變選舉的遊戲規則，推倒原有的制度。政府一方面取消選舉，同時又進行全民檢測，強調中央助港抗疫之殊遇，政策的反邏輯和時間錯配引來市民的極度反感。加上一班愚不可及的建制人士，指控不參與檢測的市民為「非良好市民」，提倡懲罰缺席「自願檢測」的市民，刺激更多本來中立的市民加入抵制的行列，一來一回是典型公關災難。

市民對今次全民檢測的反應冷淡，也是對政府未來施政的警示！自去年6月，香港政府跟六成香港人對立（以去年區選的64比例計算），而元朗721、太子831 等事件，過程被傳媒廣泛披露，於無數網上視頻亦清晰可見，仇口之大，傷痕之深，短期內無法修復。在這種敵對的情形下，政府雖獲國安法寶，可震懾示威活動，壓制反對言論，甚至趁機把反對派連根拔起，但很難消除市民對政府政策的戒心，而選擇留港的市民採取消極態度是唯一出路。

在現時極度政治化的環境下，市民對任何具爭議性的政策支持與否都必然成為變相公投。今次全民檢測，以目前的數字推算，估計最終大概150萬人參與，僅人口的兩成，數據從不騙人，大家可以藉此推算人心所向！

2020年9月8日

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** 港府於9月15日公布「全民自願檢測計畫」花費5.3億港元，當中大概3.7億為支付包括內地醫護人員費用。

Cause and effect can't be reversed!

Anyone who has some common sense would have felt very frustrated in the past one year hearing all the nonsenses from our highly paid officials. How can one be not offended when the top administrator, who receives an undeservingly high salary, could not even distinguish a cause from its effect, or a decision from an outcome as a consequence of it.

Our CE said, in defending her belated decisions in rolling out sub-optimal disease control measures, the "6-month long" fight against the virus was very well managed and delicately balanced with due consideration of our economy and other societal activities. Looks like she was very proud of her half-arsed policy that has kept us in this state for 6 months, and she knew it would take this long!

So, she was correct in delaying the border closure until early March; she was correct in allowing infinite number of people to gather indoor in support of restaurant business in June; she was so so correct in allowing 50,000+ people to travel in and out of HK unchecked in the past couple of months; she was also correct in delaying work-from-home arrangement of civil servants for a week (against her advisors' advice Monday last week). All these appeared convincing only to her blind supporters!

Anyone with an ability to think should know that the present is the outcome of past events, plus other factors of course. Didn't she know that the "6-month long fight" was the outcome? We didn't have to fight for 6 months if she agreed to implement more drastic measures earlier, and keep the measures in place.

July 21, 2020

WHO's Anti-logic

Donald Trump announces today that he will close all US borders with Europe except UK for the next 30 days in response to the threats of a severe outbreak of the New Coronavirus disease. Closing borders has proven effectiveness in cutting off the transmission chains of this contagious disease. Taiwan was the first to shut its borders completely with China including Hong Kong and Macau, and has so far remained relatively unaffected by the virus. Many countries have also partially closed their borders with China and other regions where an outbreak is known to occur.

Contagion always has a spreading end and a receiving end. If you're infected, you become a spreader and you should quarantine yourself to reduce the chance of infecting other people, or at least wear a mask. That's a responsible thing to do. But if you're healthy and wear a mask, you are protecting yourself against possible infection. Extending this logic to a national level, however, we only saw countries close their borders to protect themselves against inbound transmission, but there is not a single responsible nation who has closed its borders to prevent outbound transmission, which is what infected individuals are asked to do. Even more regretful is the irresponsible coercion to make other countries not to cut access when you knew you had an outbreak, using some totally irrelevant excuses such as racial discrimination claims or just being unkind (不厚道1—a shameful remark by a nation's spokesman). Of course the real motivation could be economical, or a narrow-minded national pride mentality, or simply selfishness.

The worst among all is the behavior of WHO, who is supposed to stand on the side of protecting people's health but had chosen to play down the situation at the early phase of the outbreak in China, and even advised countries to be cautious about making travel bans that would promote racial discrimination. Despite racial discrimination being none of WHO's business, such advice issued at the early outbreak stage was totally inappropriate and definitely not helpful in containing the virus. Instead, what WHO should and ought to do was to advise its member nations to quarantine themselves (shutting their own borders) should an outbreak occur.

The world is doomed as a result of the poor judgement of WHO and the apparent political bias of the leadership. After these few months, we clearly see the ugliness of the "big" nations, and we also know we should not take WHO's advice seriously if you still wish to survive with good health!

March 12, 2020

_________________1 「回應美國提升中國旅遊警示 華春瑩：美國實在太不厚道」— Citizen News, February 1, 2020

Will Hong Kong be in for a severe outbreak?

A novel coronavirus began to spread from Wuhan in December 2019, and now infected cases are confirmed in almost every province in China; and in the past 10 days has flown to other Asian countries and across the Pacific as well, with over 7000 people infected globally so far. Hong Kong has imported 10 cases via its many ports directly bordering with the mainland. Though Hong Kong people are vigilant of the outbreak, the painful memory of SARS has created tremendous stress and fear. The question is: will Hong Kong repeat history and be in for another severe outbreak?

Here is my quick and crude analysis, based on limited data

Data

From 22/1 to 29/1, the number of confirmed cases in HK grew from 0 to 10.

• 23/1 +2 cases, total=2

• 24/1 +3 cases, total=5

• 26/1 +3 cases, total=8

• 29/1 +2 cases, total=10

Model

My model is based on the simple rationale that new cases are related to existing cases, both within HK and imported from Wuhan. To keep it simple, I assume the bigger Wuhan area being the entire mainland. So, for Hong Kong, it is sufficient to assume just Hong Kong-Wuhan(=Mainland) interaction. So, how fast our number grows depends on

1. our own number

2. Wuhan’s number

3. recovery rate (awareness, protection, etc)

Yes, this is essentially a simplified "SIR" model*, as the academics used to call it. So, I am just pulling out the following simple equation, assuming that the incubation period is 10 days, i.e., in any day, people who can infect you are actually 10 times more than the infected number because they do not have symptom in the first ~10 days after being infected. This is just

RateHK(t) = αHK * (10) * NHK + βHK * τHK * 10 * NW – γ * (NHK+NW)

where

• RateHK(t) = rate of increase of infected cases, i.e., number of new cases per day;

• NHK = number of infected cases in HK;

• NW = number of infected cases in Wuhan (mainland);

• α, β = infection rates;

• γ = recovery rate;

• τ = traffic factor (with this parameter, I can extend the model to other cities of the entire China).

Or equivalently, by redefining parameters for simplicity's sake (only for HK anyway), we have

RateHK(t) = ΑHK * NHK + ΒHK * NW – Γ * (NHK+NW)

Now, filling in the past data (limited though), the average rates in 22-23/1, 23-24/1 and 24-26/1 are

• RateHK(ave) = 2 = ΑHK * 2 + ΒHK * 4000 – ΓHK * 0.05 * 4002

• RateHK(ave) = 3 = ΑHK * 5 + ΒHK * 4500 – ΓHK * 0.1* 5005

• RateHK(ave) = 1.5 = ΑHK * 8 + ΒHK * 6000 – ΓHK * 0.5 * 6008

The factor 0.05, 0.1 and 0.5 in the third term is to adjust the society’s awareness of self-protection that retards the transmission rate. At the beginning, awareness was very poor in the mainland, I would say 0.05 as the factor of awareness that reduces the recovery rate. Then, in later few days, people get better educated, say being improved to 0.1. Then, at the latest time, I assume that most are vigilant, hence 0.5. This factor is necessary unless we make alpha and beta time-varying to address the same effect.

Solving the equations from the data, we get ΑHK = 0.405, ΒHK = 0.0003782, and ΓHK = 0.0016.

Prediction

So, here we go (assuming full awareness of self-protection):

RateHK = 0.405 NHK + 0.0003782 NW – 0.0016 * 1.0 * (NHK+NW)

Just a bit of nasty arithmetics, averaging over next 30 days, NHK should be adjusted to NHK(now) + RateHK*15. So, the next 30 days, we have

RateHK = 0.405 (NHK(now)+RateHK*15) + 0.0003782 NW – 0.0016 * 1.0 * (NHK(now)+RateHK*15+NW)

Assume Wuhan’s outbreak continues in the next 4 weeks. Let’s speculate 3 scenarios, depending on the mainland situation and assuming that our borders remain opened (at least our CE had insisted it be so).

1. WORST: For extreme outbreak, let NW = 100000 average in Feb.

2. POOR: For severe outbreak, let NW = 50000 average in Feb

3. HOPEFUL: If outbreak in Wuhan (mainland) is under control, let NW = 10000 average in Feb.

PREDICTION of Rate_HK for next 30 days:

1. WORST: RateHK = 15 cases per day

2. POOR: RateHK = 7 cases per day

3. HOPEFUL: RateHK = 0 cases per day (as RateHK < 0)

Conclusion

I don't have enough data to establish a confidence level. Perhaps somewhere between HOPEFUL and POOR is the most likely event, as the mainland number continues to soar over 10,000!

I must also confess that I did not consider the contact network and individual behavior in the above analysis. So, not perfect though, still I would say they aren't completely unreasonable estimates.

30 January 2020

__________________*M. Small, P. Shi and C. K. Tse, "Plausible Models for Propagation of the SARS Virus," IEICE Transactions on Fundamentals of Electronics Communications and Computer Sciences, vol. E87-A, no. 9, pp. 2379-2386, September 2004.M. Small, C. K. Tse, and D.M. Walker, "Super-spreaders and the rate of transmission of the SARS virus," Physica D, vol. 215, pp. 146-158, March 2006.