The first cut is the deepest
It is always a nice feeling to be able to say you were right. In a recent opinion, I set out the mathematical basis for the construction of a useable model to track the evolution in a society of Sars-CoV-2. It was my primary point that there was no basis for the declaration of the state of emergency based on the publicly available figures.
This did not come from out of the blue. I had been personally affected by policy. I, myself, was taken ill on Thursday, March 19 and a test carried out at the hospital on March 21 returned negative.
I then went through three weeks of bizzaro world. Five days of sweats and fever, unable to get up in the morning from pain, etc. Then Day 7 arrived and, almost magically, all was suddenly fine. There then followed two weeks of laboured breathing, exhaustion, hallucinations and talking about events that never happened. It culminated in something of a character change that made me super angry at the most banal provocation.
In other words, I had the disease, Covid-19.
I was a false negative and no one near to me was tested, not even my partner, a nurse at the King Edward VII Memorial Hospital. To date she has never been tested, as she heads out for an all-night shift in the Covid-19 intensive care unit.
My next point was that there was no evidence of any exponential growth in infective people. To be clear on the Government抯 own figures, the rate of increase in infectives was slowing and was below 1; in fact a long way below 1.
I speculated that the only circumstances that would justify the state of emergency was the known existence of false negatives and the time bombs represented by the air arrivals who had gone out to the clubs and bars instead of staying quarantined.
On a number of occasions, I met such people in the clubs and bars. Thus, any ongoing infection pattern was coming from false negatives and those air arrivals. That I was contacted and told to treat my test as positive and the next air arrivals were quarantined by the Government and placed under guard tells me I was right. This means that we were locked in because our government had no idea what the real data looked like
My own personal analysis of the situation was that, on the basis of an SIR (susceptible, infective, removed) model, the famous metric known as Ro ?pronounced 揜 nought??had never been above 1, and therefore there had never been at any point when a disease was spreading, let alone spreading at any rate exponentially.
Now, it is true that Bermuda抯 sample size is so small that the standard deviation from the mean with any pocket of infection would be significant. It remains the case that Bermuda抯 value for Ro has never exceeded 1. It complies entirely with my prediction. The Government has now produced its model, the very model I suggested it was using and which has been much criticised. A very quick glance reveals that it is wrong in about every way that it is possible for such a model to be wrong.
I will not bore the public with the mathematics again but a reasonable explanation for the method of creating a model is found here. If you take the trouble to watch it, you will see very quickly how a non-mathematician would either lose interest or understanding.
The stated purpose of our own lockdown, which was largely adhered to, would be to allow two cycles of infection ?the second 14 days would catch those who would have been in the second generation. That is, those who had been infected by a contact of someone who was either false negative or an air arrival. It nearly worked
However, we now know that four people have tested positive in five days last week. We also know that their contacts have not been traced. It is very likely that they were tested as a result of having been traced. This allows us to make a number of clinical guesses.
First, if they tested positive, they had a sufficient viral load to be contagious and it is likely that they had been contagious for a number of days. This allows us to guess that they have passed the virus on. It will depend on their life and work conditions, but I would surmise they have passed it on to two people each, at least because one person seems to have passed it on to these four.
We can also surmise that they were infected in one of our care homes. The homes where the health minister has told us that testing will not be complete for two more weeks. I am afraid that really isn抰 good enough. I will predict that we should see approximately seven to ten new cases in Bermuda in the coming week to ten days, and that number will double in the next week to ten days ?it will depend on the speed at which symptoms come on and thus the length of time that they are contagious but don抰 know it.
I hope I am wrong.
The reason I hope I am wrong is because the Government has just relaxed rules that will increase contacts between two households massively and between susceptibles and infectives significantly. The most observant of you will recall that I called that rate 搑?in my last opinion. The whole purpose of the lockdown has been to drive down the number of contacts that may occur between those of us who are infective and those of us who are susceptible to infection.
It would seem that the health minister has failed to understand the structure of her own model and her own strategy for controlling the rate of infection. It remains the case today that there are active contacts of four people who tested positive for Sars-CoV-2 who have been neither tested nor isolated, which is an essential element of the strategy.
Test ?Trace ?Isolate.
What you need to know is the difference in the number of infectives over time. As I say, getting from these simple concepts to a figure for Ro, as it has come to be known, is fairly complex. The economic damage associated with the lockdown is yet to be ascertained, but will be substantial and some places will be gone for ever.
Certainly, on the results, it is difficult to criticise the public health benefits of the lockdown. It would not be possible to criticise its continuation when a person tested positive on April 28. The question is, whether it will be possible to criticise the decision to relax the lockdown when it is known that there are infectives in the community and we do not know who they are.
This was entirely predictable on the publicly available information. For the plan to have worked, we needed to have at least one rotation where the infectives?number was decreasing.
The disease seems to have been spread through the care-home network ?some of whom tested positive as early as April 21 ?and it should have been obvious that those who were infected and allowed to go home would infect others. They did, as the four who tested positive have connections with the care-home system. Indeed, the number of walking newly infectives over that two-week period could be vast.
Having got this far, what is the next question that is vexing our government抯 mind? It must be how do we open the gates again and 搇et my people go? as I once heard someone put it? It is a very difficult question for a government that manifestly does not understand its own model or its own strategy. The strategy was to keep us incarcerated until the disease had been stamped out. We nearly did it, but instead we know that we are being released into a world inhabited by infectives. We also know that we are all susceptible.
Are we ready to make that first deep cut in the controls?
In a recent series of articles on the free online posting site Medium, Tomas Pueyo, who, like me, is not a professional mathematician or an epidemiologist, sets out a strategy that he calls 揟he Hammer and the Dance?
It has been taken up by many governments as a viable strategy for the opening of an economy, and sounded a little like what was described by Kim Wilson and the Premier. As a precondition, you need to see falling rates of infection, fewer infections in total, and this over a period of 14 days.
Next you need a massive testing regime ?in Bermuda probably in the region of 2,000 a day, and I am being generous; it is likely to be nearer 3,000. You then need to track down, within 24 hours, all of the infectives?contacts over the past five days ?who will then be tested ?and isolate those contacts for 14 days. For those who test positive, you trace their contacts and keep going. The reason you have to do it within 24 hours is because you need to prevent a second generation.
The 揾ammer?is what we have just been through. Everyone stays home and the economy is effectively put on ice with the massive consequences that we have all seen and felt. The 揹ance?is the system of allowing more freedom of movement, and thus contact, but only when appropriate.
As the value of Ro falls further below 1, the freedoms are increased. Where it rises, there will be the immediate re-implementation of stricter limitations on movement, and thus contacts. This is effectively what they have been doing in South Korea and also to a lesser extent in Singapore. It is what is proposed by the Government. In other words, if it goes up, it will be our fault.
Wrong! It will go up because the SIR model predicts it and it is all but certain.
揑t all sounds so easy,?I hear you cry. 揕et us get on with it. What do you know, you are just a self-important lawyer??/p>
I do not have certainty but for the strategy to work, even in the right conditions to relax restrictions, there is one important massive catch: there must be a systematic massive testing regime that allows for the identification of infective individuals. Once an infective is identified, there must be an even more massive regime of tracing their contacts. Once found, those contacts must be isolated, and that will require a system of policing the isolation and testing of those contacts.
We have no meaningful system of tracing those people that an infective has come into contact with over their contagious period. Say we have six teams of five. If one infective person has contact with 30 people a day and, because they will meet the same people a number of times, their contacts for a week will be about 150 different people. They all need to be traced and isolated within 24 hours because there is no point leaving them in the community.
Even if they test negative the first time, they will need to be retested every day. Remember, it may be possibly the failure or inability to police or supervise the returning students that led to the supposed need for the state of emergency in the first place. This is super-important.
We do, however, have one silver bullet in this department. We have a young Bermudian PhD working in Britain who has returned to the island, taken her quarantine, and has now established a laboratory. Carika Weldon is a credit to the land from which she hails, to the system that brought her up and to herself and her parents. It is my belief and hope that she is capable of great things and we will need great things if we are to do this properly.
For my part, I say as loudly as I can ... ?i>Chapeau? to borrow a phrase from our Gallic friends. She should be given some kind of award for caring about her land and her people. She should also be given responsibility for making these kinds of decisions and she should get a helper in the shape of both a clinician and a proper mathematician who can speak the language of nature ?mathematics.
These are all very difficult decisions.
The evidence is not encouraging. It is going to take weeks to test the staff and residents of the care homes and you already know who they are. What damage will they have been done in the meantime? Again, only if you are testing way more than we are and probably almost 2,000 a day can any meaningful decision be made.
The Government now has at least one Bermuda expert. We should put her in the forefront because she really does know what she is talking about. Find another expert who speaks the language of nature and understands these models and how it can be calibrated to loosen the yoke of bondage. A mechanism to loosen it so that we do not have to go back to it again.
This is new to all of us. However, you can watch New York governor Andrew Cuomo, for example, tell his people that he does not know what he is talking about, and he is listening to experts and he tells us what they are saying. He tells the truth about testing and the availability of proper equipment.
There is another technique, much enjoyed by the well-coiffed, indeed miraculously coiffed, orange marvel that is Donald J. Trump. Let them drink Lysol, he cries, it kills the virus in seconds. Or was it inject it? Who would you rather be, David Burt?
It is the language of mathematics that will find the pathway out of this mess we have been got into. I implore the Government to find someone who speaks that language and to get them to speak to Dr Weldon. Between them they will allow us to take the next step with confidence.
The ethical, scientific, economic, and sociological consequences of this disease are vast. Our government seems to have stumbled to a reasonable position. It is the first of the next steps that requires the most care.
Do not drop the ball, do not imagine you know what you are doing, and take advantage of every resource you can. Do not cut too deep. The less fortunate among us need your government. Do not let them down by getting this wrong because we know who suffers most.
?Cameron Hill is self-employed Bermudian lawyer who possesses an undergraduate degree in Applied Mathematics/Econometrics and a master抯 degree in European social policy. He was admitted to the bar in London in 1996 and in Bermuda in 1999, and in Scotland, where he still practises, specialising in insolvency law at the Court of Session
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