MD, PhD, FMedSci, FRSB, FRCP, FRCPEd.

Boris Johnson said we should take the coronavirus ‘on the chin’ and count on ‘herd-immunity’. This, he claimed, is what his scientific advisers recommended.

I find this very hard to believe and have many doubts and questions.

To start with, I doubt that this is what Johnson’s scientific advisers recommend – it is a solution that SOME of his scientific advisers recommend. And it is a solution that seems easy to follow. It is, however, by no means the only strategy for tacking the pandemic; it is just one of several options.

The fact that all other countries have opted for other solutions, suggests to me that it is an unusual path to go down to. The modellers who obviously like it had to make a number of assumptions; that’s what modellers always have to do and rarely tell us about. But what if not all of these assumptions are correct?

The herd-immunity strategy counts on the fact that, once a certain percentage of the population has taken the infection ‘on the chin’, it is immune and therefore the transmission of the virus within such a population will be dramatically reduced or even zero. The percentage of the population needed for that to happen depends on how contagious the virus is. For the measles virus, herd immunity requires 90% of the population to be immune. For the coronavirus, the figure is said to be 60 – 70%. Is that an assumption or a fact? If it is a current fact, would the figure change, if the virus mutates? Could it be that a mutated virus can re-infect formerly immune people?

But let’s postulate that the herd-immunity assumption is both correct and stable. Johnson’s herd-immunity strategy would thus require that about 40 million Brits get infected with the virus to generate the required herd-immunity. Assuming a mortality rate of 1 – 2%, this means that Johnson is cheerfully accepting 400 000 – 800 000 fatalities.

But, as I said, this scenario is based on wild assumptions. It applies only if the virus does not mutate. And it only applies, if we do not run out of intensive care (IC) beds. However, running out seems possible, perhaps even likely, considering that we have only about half of the French and just one third of the German IC capacity. Sod’s law has it that both might happen. In this case, we might easily have far in excess of 800 000 fatalities. How should we take that ‘on the chin’, Mr Johnson?

Sadly, this is not all; I have further doubts about our PM’s ideas.

The present strategy regarding diagnosis of coronavirus cases is to self-isolate once suspicious symptoms start. Even if someone is seriously ill (with high fever etc.), they are told to stay at home and sit it out. This means we will never know whether these patients had or had not suffered from a coronavirus infection. How then can we ever be sure that the 60% target of infection has been reached? And if we are uncertain about it, how can we be sure that herd-immunity will work in the way the modellers predicted?

Moreover, we now know that people who caught the virus are infective BEFORE they develop symptoms. If that is so, the strategy of self-isolation will be far less effective than predicted. And, given this fact, are we not much more likely to have a sharp peak of cases early on which would make us run out of IC capacity? When that happens, even the pessimistic death rates might turn out to be too optimistic.

It seems to me that Johnson’s herd-immunity strategy is risky to the point of being reckless. It also seems to me that there are very good reasons why other countries have not adopted it.

But what is the solution?

In my view, the solution cannot be to uncritically adopt the theories and assumptions of modellers. This is not a computer game; we are talking about human lives, many human lives!

I wish I new what the best solution is – but I don’t. I merely fear that ‘taking it on the chin’ is not a solution at all. In any case, a wise move for Johnson and his team might be to consider that foreigners might be at least as clever as they are. Subsequently they could carefully study the actions of those countries which managed to bring down their death-rates despite being attacked by the coronavirus.

46 Responses to The coronavirus, Boris Johnson, herd-immunity, doubts and questions

  • IT IS reckless, and stupid. On which basis he can affirm that an immunity will even exist? We do not know if an immunity develops after infection, or how long it lasts. It is a coronavirus, and we know well that we do not develop long lasting immunity against common cold. This is going to be a massacre.
    From Italy’s red zone.

    • thank you – and best of luck to you.

    • On which basis he can affirm that an immunity will even exist? We do not know if an immunity develops after infection, or how long it lasts. It is a coronavirus, and we know well that we do not develop long lasting immunity against common cold.

      Davide,

      I am afraid that you are not very well informed about the common cold. There are hundreds of viruses that can infect the upper respiratory tract causing a limited illness with a common collection of symptoms including sore throat, cough, runny nose, blocked nose, sneezing, malaise, infection, sometimes fever… These are all lumped together under the umbrella of the common cold, or coryza as it is technically called. Once you have had one of these infections, you become immune to it, but it doesn’t protect you against any of the others.

      This is clear if you look at what happens to small children once they are old enough to attend kindergarden or primary school. They easily catch every type of cold that circulates, and on average they will have about six coryzal infections per year. Their parents, on the other hand, are already immune to most of these, and only catch one or two colds a year (on average) as do most adults. Note that this is an average, and it is not uncommon to have no cold one year and three colds the next.

      Many of these viruses are from quite different groups (adenovirus, enterovirus, respiratory syncytial virus, parainfluenza etc.) and coronavirus is one of them. The coronavirus that caused SARS, and the current Covid-19 pandemic are different in that they are able to cause a more serious illness, but there is no reason to suppose that anybody with an intact immune system will become immune long-term following an infection.

      • I’m afraid he is precisely correct. We do get recurrences of the common cold (which is not “technically called” coryza, that’s a description of a group of symptoms). The common cold stays in business by adapting itself so that our immune systems fail to recognise it at the next attack. It’s unfortunately quite possible that this novel coronavirus will follow the same pattern. We just don’t know yet, and we should build this lack of certainty into our planning response

        • You are right about coryza, which is a strictly speaking a feature of most colds (i.e. runny nose, congested upper airways etc.), as distinct from cough.

          However, the common cold is not a single disease, and usually each infection that an individual experiences is with a different virus rather than a mutated form of the same one. Unfortunately I have had three hospital admissions over the past couple of years with virus infections (I am significantly immunocompromised) and DNA sequencing showed two of them to be different types of parainfluenza and one to be respiratory syncytial virus. I have had permanent damage from one of them. However, most people with these infections would simply think that they had had a heavy cold which they wouldn’t distinguish from any other cold.

      • Did you leave out a “not” in your last line there?

        wg

  • Johnson’s comment about ‘taking it on the chin’ has been taken out of context: Here is the transcript of what Boris Johnson said on This Morning about the new coronavirus – Full Fact

    What he said was:

    Well it’s a very, very important question, and that’s where a lot of the debate has been and one of the theories is, that perhaps you could take it on the chin, take it all in one go and allow the disease, as it were, to move through the population, without taking as many draconian measures. I think we need to strike a balance, I think it is very important, we’ve got a fantastic NHS, we will give them all the support that they need, we will make sure that they have all preparations, all the kit that they need for us to get through it. But I think it would be better if we take all the measures that we can now to stop the peak of the disease being as difficult for the NHS as it might be, I think there are things that we may be able to do.

    I also caught a bit of a programme on Radio 4 a short time ago where the representative from the WHO said that the UK was basing their strategy on the best available science and evidence (and either he or someone else said other countries were not). I’ll try to find a link later.

  • Sadly, it seems both of our nations’ leadership suffer from a similar lack of accountability and gravity. The MO at the federal executive level in the US, thus far, seems to be deny, refute, downplay and gag those with clear expertise. This, after eviscerating the positions and departments necessary to mount a rapid and coordinated response to such pandemics. Troubling to me is the federal position of pushing responsibility to the state level, and states shoving it onto the counties and municipalities on the premise that the response needs to be managed on the local level as every community is “different”. Hogwash. I’m sure COVID-19 is an equal opportunity virus.

    At least bold steps are now being taken (as my teens prepare for at least a month of home study), but, I fear, far, far too late. tRump’s lackluster and irreparably late declaration of a national emergency was done only, IMO, to appease the stock markets and, by extension, his cronies and toadies.

    Earlier on, I sought out what I believe to be credible sources which resulted in me imploring my 92-year-old mother to just stay in for now on the condition she may freely laugh at me if it turns out I am overreacting. So far, I don’t believe I have.

  • The fatalities would be 800,000. Besides, there is absolutely no doubt that we would run out of ICU beds. The strategy is predicated on having the epidemic peak in summer. The UK has approximately 4000 ICU beds, 3000 of which usually occupied (this is NHS data). Suppose they manage to miraculously provide 4000 free at all times though. If everyone spends even only one week in them, and out of 4 million, 5% needs them (a fair assumption, in line with the rest of the world’s statistics), then that’s 2 million people, or 500 weeks, or slightly short of ten years. Certainly not enough time to do this for summer unless we can somehow churn out one or two order of magnitude ICU beds in weeks.

    • thanks; I corrected my mistake

      • The broad assumption of about 2% of the infected dying is not valid. The data from different countries is now showing a pattern and the China experience can be used to come close to understand the direction of action.

        The data shows a clear pattern, when comparison is made between South Korea, Italy and Singapore.
        There is no doubt that if infection is contained by proactive action, deaths can be controlled. Singapore provides a good example.

        Isolating infected patients and providing focused medical attention to those who require it saves deaths as it frees medical attention and resources for those who really need it.

        The profile of people at risk is very clear now.
        “Data from China, where the epidemic began, show death rates that are startlingly higher than the average for people age 60 and over, as well as for people with high blood pressure, diabetes, asthma and other chronic conditions. In one large study by the Chinese Center for Disease Control and Prevention, 14.8% of people 80 and older and 8% of people 70 to 79 died. For people with cardiovascular disease, the mortality rate was 10.5%, and 7.3% for those with diabetes. Those rates compared with a 2.3% mortality rate in the overall population of 44,672 patients studied through Feb. 11, China’s CDC says.”

        NHS/hospitals, should have data for such patients and City councils of the elderly. Use this data to build target groups, to focus attention for isolation, medical attention and resources on these target groups and therefore individuals.

        Population falling outside these groups should be treated, as would, for a regular case of flu. Provide sufficient and clear information to the people about isolation, hygiene, assessing condition and helplines and support to help those in real need.

        “In this case, we might easily have far in excess of 800 000 fatalities. How should we take that ‘on the chin’, Mr Johnson?”
        What is your basis of this calculation of 800,000? Your ideology that does not accept Brexit or anyone connected to it, like Mr Johnson? The proper transcript shows very clearly that there is nothing like “taking it on the chin”? Provide some sensible data review, instead of fear mongering (800,000 would die). This did not even happen in China who took the blast “on the chin” before initiating clumsy steps and then, out of fear, becoming utterly ruthless to save the balance population by locking down the population suspected of infection.

  • It might have made the reality of Boris’s let them “take it on the chin” analogy more realistic had he said:

    “We must let some people, but hopefully not me or my loved ones, take it in the lungs”.

  • I think the government really should release the models and assumptions they’re working from for public scrutiny. Britain is full of quite brilliant scientists and medical researchers, and getting them to consider and critique the work would be using the scientific method as it’s meant to be used.

    wg

  • Ahhh, the usual tactic of ignoring the ‘elephant in the room’ which in this case means encouraging the Public to either wait until they get infected or die. The elephant in the room of course is our own innate immune system. The corona virus or any mutation of it will not wipe out the human race. This is because viruses are smarter than we are, they need a live host to maintain their survival, so it isn’t in their best interest to kill us all!
    Most infected citizens will survive this and other virus infections, so how is that possible?
    There is a strategy hardly ever mentioned by so called health professionals. First, consumers should educate themselves in the workings of their own immune system (that is a no-brainer). Then they should check regularly their Serum 25(OD) Level to maintain a minimum of around 60 ng/mL (America) or 150 nmol/L (UK). Then work with a specialist in the field of gut health – i.e. check the state of their microbiome.
    Doctors in the UK seem strangely reluctant to even discuss the fact that many deaths are also associated with ‘underlying health issues’ – in other words these people will likely have a compromised or weak immune system. Concerned about the virus? Time to get real!

  • This pandemic raises so many questions.

    Are the ICU bed numbers you quote corrected for population or just raw numbers and if not corrected, how would that affect the picture? The relative age distributions in the population would be another important variable.

    It is obvious there are many complex factors and interactions to consider, but one part of many countries strategies raises a question for me. If schools are closed that generally means either a parent has to stop work or it is likely that in many cases grandparents may step in to help with childcare. Is this likely to be a significant contribution to risk for the elderly?

    Am I right that I recall passage through a young animal of a pathogenic organism, was used as a way to select more virulent strains and, outside of possible military use, used to develop more effective vaccines? So could increased contact from younger children potentially increase the risk to older people even further – or at least hasten what might happen eventually anyway? I think it is early days and information on if the virus is already changing or not is not available. I know families who have already reduced or stopped contact with elderly relatives as a precaution, but closing schools may mean limited choices for many families.

    Sorry if these are näive points, but the complexities can quickly become mind-boggling.

  • Edzard,

    For once I have to take issue with your uninformed and in my view irresponsible post.

    The herd-immunity strategy counts on the fact that, once a certain percentage of the population has taken the infection ‘on the chin’, it is immune and therefore the transmission of the virus within such a population will be dramatically reduced or even zero. The percentage of the population needed for that to happen depends on how contagious the virus is. For the measles virus, herd immunity requires 90% of the population to be immune. For the coronavirus, the figure is said to be 60 – 70%. Is that an assumption or a fact?

    With regard to herd immunity, you are quite correct that a large proportion need to be immune in order to protect the rest. Essentially it depends on how many additional infections each case (on average) generates. If it is more than one, then a chain reaction results and the number of cases increases exponentially (as is happening now with Covid-19). If it is fewer than one then the chain of infection will fizzle out and cases will become sporadic. The proportion of people who need to be immune varies depending on how contagious the infection is. With measles, as you say, it is over 90%. With Covid-19 we don’t know, and I have heard various estimates from epidemiologists in the range 40 – 70%.

    would the figure change, if the virus mutates? Could it be that a mutated virus can re-infect formerly immune people?

    So far the genome of this virus seems remarkably stable, with samples from all over the world matching the DNA sequence that Chinese virologists published at the beginning of the outbreak. It is certainly quite different from the influenza virus in this regard, which is very unstable compared to most viruses.

    But let’s postulate that the herd-immunity assumption is both correct and stable. Johnson’s herd-immunity strategy would thus require that about 40 million Brits get infected with the virus to generate the required herd-immunity. Assuming a mortality rate of 1 – 2%, this means that Johnson is cheerfully accepting 400 000 – 800 000 fatalities.

    Boris may be accepting this figure as realistic, but I doubt that he is cheerful about it. I would not be at all surprised if it turns out to be about right.

    Since this outbreak has gone beyond the point at which there is any chance of containing it, it is INEVITABLE that it will ultimately affect a very high proportion of the population. That means that a lot of people are going to be seriously ill and a lot of people are going to die. Any public health strategy can therefore only limit the damage.

    Obviously it would be nice if the spread could be slowed down enough to allow the development of vaccines, or of any type of effective treatment (for instance immunomodulatory treatment to mitigate the cytokine storm that is responsible for penumonitis, adult respiratory distress syndrome (ARDS) and multi-system failure in the sickest patients. While vaccines are still 12 – 18 months away, it is quite possible that ways of reducing the death rate in the sickest patients can be found sooner than this (there are many lines of research here). Therefore slowing it down at all has potential benefits.

    However, in the meantime we know that good medical care, including intensive care treatment and ventilation where necessary, does reduce the number of deaths. We also know that facilities for this, in Britain and worldwide, are limited. Therefore it is vital that we do all we can to prevent a situation where everybody gets the infection at once (remembering that this includes healthcare staff) and the NHS is overwhelmed. This is what the Government is trying to do, so that as people require ITU beds and ventilation they will be there for them.

    What we know from other outbreaks tells us that the obvious, common-sense measures are not necessarily the most effective ones. For instance, closing borders has not in the past proved effective in keeping infections out, particularly since anybody crossing a border illegally is not readily going to come to the attention of public health agencies.

    China was able to gain control in Hubei Province by instigating draconian measure that are simply not possible outside a totalitarian regime, but regardless of that any form of isolation and limitation of movement comes with a cost. We are already beginning to see a huge hit to the global economy, which will inevitably have long-term effects of all kinds. Some of these effects will certainly be on our health. Prosperity has been found to be strongly correlated with health and longevity in epidemiological studies in all societies.

    Boris Johnson has also pointed out that people tend not to be able to sustain effective isolation measures beyond a limited period of time. I have no idea whether it is true, but all that I have learned over the course of my life and my 30-year career as a doctor is that people don’t behave the way that you think they are going to or how you think they ought to, and if this is what his advisers are telling him I am prepared to believe it is true. (Whether it is wise for him to say something so counter-intuitive in a speech to the Nation is a different matter and I don’t feel qualified to have an opinion here.)

    I should point out that there are many reasons why the UK should not necessarily take the same measures as other countries. For a start, each country is doing things differently anyway, so who should we follow? We are also unique in having not only the NHS, but also an effective nationwide public health system (note that Public Health is about prevention of illness, as opposed to Healthcare, which is treating it). Our geographical position as an island is also a factor. Finally I should point out that the Conservative Government has recently won a general election with a comfortable majority, and Boris therefore does not have to worry as much as many other heads of state about taking decisions which the electorate might not agree with (or understand). This is not always a good thing, but my impression is that in this case the Government, for once, is following the advice of its scientific advisers rather than basing its decisions on ideology or popularism.

    I should also point out that the advice we are getting from the Government is changing daily in response to the changing situation.

    The present strategy regarding diagnosis of coronavirus cases is to self-isolate once suspicious symptoms start. Even if someone is seriously ill (with high fever etc.), they are told to stay at home and sit it out. This means we will never know whether these patients had or had not suffered from a coronavirus infection. How then can we ever be sure that the 60% target of infection has been reached? And if we are uncertain about it, how can we be sure that herd-immunity will work in the way the modellers predicted

    There is no 60% target. We will know when herd immunity is starting to have an effect by looking at the pattern and rate of spread of infections, which is what epidemiologists always do. Unfortunately the way the media are reporting this outbreak tells us very little about what is going on here – we need to look at changes in the slope of logarithmic case curves broken down by country and community to understand what is happening, though most people don’t have much of a feel for exponential growth and the way these numbers behave. As an example, if the numbers within a country are doubling every 4 days, then it takes the same time to increase from 20 cases to 40 as it does to go from 20,000 to 40,000. Furthermore, for every 10 doublings (40 days here) that means an increase in cases by a factor of a thousand, and 20 doublings are an increase by a factor of a million. So if you work out the number of cases you should expect in a month’s time, and then wait to see what actually happens, you will know whether the Government is doing a good job or not.

    I think your idea of seriously ill might be a bit different from mine. I wouldn’t be concerned about a high fever on its own, nor by somebody feeling lousy, providing that they weren’t deteriorating, they were able to drink enough, they were passing normal amounts of urine and they could still breathe comfortably. Hopefully the NHS 111 helpline will be able to cope with the demand and be there to advise people when they should seek hospital care.

    In my view, the solution cannot be to uncritically adopt the theories and assumptions of modellers. This is not a computer game; we are talking about human lives, many human lives!

    Is this really the same Edzard Ernst talking here, who puts evidence above everything when it comes to healthcare? Epidemiologists are doctors and statisticians who devote their careers to the study of patterns of disease, and to collecting and interpreting the evidence on which public health advice is ultimately based. In the process they have contributed more to the improvements in our health than any other branch of medicine. Common-sense, intuition and emotional reaction and panic are strong forces, but only numbers and evidence can lead us to effective decisions, and epidemiologists, who understand them, are the people we need to listen to.

    I have just read your post again. It clearly shows how hard it is to remain dispassionate when we feel personally threatened, and how easily any one of us can let go of reason when circumstance conspires against us. Perhaps it isn’t so hard to understand the mindset that might cause a parent to worry whether their doctor is recommending unsafe vaccines for their child, or whether, after we have been told that our cancer is incurable, there might after all be something in the diet or the therapist that our friend is recommending. Unfortunately we all know where this can lead.

    • thank you for you opinion.
      I do not share it but thanks anyway.
      to correct you on just 3 points:
      1) I do not think my post is irresponsible at all.
      2) I feel not personally threatened by Johnson’s corona-party simply because I am not in the UK and ave no intention to return in a hurry.
      3) I understand epidemiology probably better than you think, as I was involved in lots of epidemiological research years ago (https://pubmed.ncbi.nlm.nih.gov/10848841-association-between-plasma-viscosity-and-all-cause-mortality-results-from-the-monica-augsburg-cohort-study-1984-92/?from_term=ernst+e%2C+monica&from_pos=6)

      • Edzard (and Jashak),

        On reflection I think my language was a little harsh.

        The main thing I take exception to is your dismissal of epidemiologists and their modelling:

        In my view, the solution cannot be to uncritically adopt the theories and assumptions of modellers. This is not a computer game; we are talking about human lives, many human lives

        Human lives are the bread-and-butter of epidemiologists. They aren’t clinicians, so they may not know them individually, but they deal in much larger numbers and so their work has a proportionally greater impact.

        Epidemiology is at the heart of evidence-based medicine. It is how we are able to understand the spread of infectious diseases such as malaria, TB, ebola, flu, HIV and many, many others. It is also how we know what factors influence the development of other major killers such as heart disease, cancer and diabetes. Modelling the data tells us, for instance, that Covid-19 is spread by close proximity, in contrast to ebola, for instance, which requires contact with body fluids.

        I certainly agree that no medical research should be uncritically accepted. But in this area there are not many people who have the right expertise to criticise. Certainly I don’t.

        We have heard from virologists and immunologists (who are also not necessarily clinicians). They are the ones who will develop vaccines against this new disease, and who stand the best chance of understanding why 80% of people get a mild illness and 20% go on to develop what appears to be a cytokine-mediated pneumonitis, and therefore what measures might mitigate the mortality rate. But they don’t have the experience of a career devoted to the study of how disease spread is influenced by population demographics (age structure), geography, cultural influences (behaviour), nutrition, co-morbidities and more. It is the epidemologists, with their models, who have access to the relevant data, and who understand how to deal with it.

        If we don’t listen to the modellers when we seek advice on how best to protect ourselves, as individuals and collectively, then who do we listen to? Everybody has opinions, but not everybody has the relevant expertise, not even experts in other areas of infectious disease research.

        • “Human lives are the bread-and-butter of epidemiologists”
          believe me, that’s not true!
          they deal with numbers, not with lives nor with deaths.

          • How are numbers not about lives?

            Think of the numbers that tell us what is happening with climate change, or the numbers that tell an aeronautical engineer whether a plane will remain airborne, or the numbers generated by a clinical trial that tell clinicians like me what treatments we should use (or indeed whether the conclusions of the trial are meaningful at all). Numbers determine so many aspects of our lives, even though we may be unaware of them, and it is vital to understand them in order to make rational decisions.

          • ok, you don’t want to understand me. fine!
            you think calling me ‘irresponsible’ is a ‘little harsh’. fine!

        • “If we don’t listen to the modellers when we seek advice on how best to protect ourselves, as individuals and collectively, then who do we listen to?”
          to those guys who are setting the example of bringing down the numbers of fatalities during the pandemic; to those countries that demonstrate the success in dealing with the crisis. not to those who feel like running an exciting experiment that no other country adopts. do you not wonder why the UK is the only country that goes down this route? well, I do!

          • I have been having a look at this Web site:
            https://www.worldometers.info/coronavirus/

            which has a wealth of epidemiological information about this disease, and which seems to be updated every few minutes. For me, the best thing about it is that many of the graphs of numbers against time can be shown on a logarithmic scale as well as a linear scale. This is a much better way of presenting the data as it allows you to get a rough idea of what is happening at a glance. Where growth is exponential (i.e. case numbers increasing at a constant rate) the logarithmic scale gives a straight line, and the rate of increase (probably best expressed as a doubling time) can be derived from the slope. Any changes in the slope indicate changes in the rate of transmission (well, diagnosis – or death, depending on the graph), so it is relatively straightforward to see if containment measures are working.

            For example, if you look at the graph for China, case numbers were increasing exponentially at first. However, from around the beginning of February the straight line began to curve, indicating that they were starting to control the outbreak at that point. You would never realise this just looking at the raw numbers; at the beginning of February China had had about 17,000 cases, less than a quarter of the current number (as of mid-March). A linear graph isn’t much help here, either, since the slow-down isn’t really apparent until three weeks after it started.

            For the countries where this curve is given (China, S. Korea, Iran, Italy, France, Germany, USA and UK) there seems to be a fairly consistent pattern. Once the phase of exponential growth has become established, in every case it takes about 9 days for the numbers to increase by a factor of 10; this equates to a doubling time of about 2 days. The earlier part of the curve (prior to the exponential phase) seems to take a variety of shapes, probably depending on how easy testing and diagnosis were in that country at that time (with additional random variation, since the numbers initially are small).

            With the exception of China and S. Korea, the other countries where the graph is available are still in the exponential phase, indicating that whatever measures have been instigated so far have not (yet) had any effect.

            What happens when we extrapolate into the next few weeks is very worrying indeed. Let us look at the UK:
            On March 5th there were 116 cases. On March 14th this had risen to 1140. The curve in between is roughly a straight line, so rather than using linear regression on all the points in between it is a reasonably good approximation to say that the numbers have gone up x10 in 9 days (or roughly doubling in 2 days).

            This evening I saw Boris Johnson on the BBC news saying that if we don’t put proper control measures in place we could reach a point where the numbers are doubling every 6 days. This is clearly not the case as they are already doubling every 2 days, and have been doubling at this rate since 26th February. He is also inaccurate in telling us that the UK is a month behind Italy – it is only about 10 days or so.

            So where does this leave us? 10 doublings is a rise of x1,000 (1024 to be exact), and this is in three weeks. 20 doublings (six weeks) represents a rise by a factor of a million. As of now (end of 16th March) we have had 1,543 cases, so we should expect to see about 1.5 million cases by the end of the first week of April. By the end of April the number of cases would be be 25 times the population of the UK, which is clearly impossible. We know, however, that once a sufficient proportion of the population have had it (assuming that they are immune by then, which on this timescale they must be as they wouldn’t have recovered in the first place otherwise) the transmission rate falls. When it drops below 1.0 (i.e. each case infects fewer than one other person on average) then transmission can no longer be sustained and the epidemic fizzles out. This is the effect of herd immunity, and will have the effect of slowing down the rise so that it peaks later. In technical terms the exponential curve become Gompertzian (exponential growth multiplied by exponential slowing). However, I don’t have the expertise to crunch the numbers here.

            What about death rates? Looking at closed cases (i.e. either dead or recovered) the death rate seems to vary enormously between countries. This does not, however, indicate that some countries are better at treating the infection than others, since there are many statistical factors which will alter this figure. One very important factor is the rate of diagnosis. If only the relatively severe cases are diagnosed, and the mild or asymptomatic ones go unrecorded, this will make the death rate appear to be much higher than it really is. Since the case numbers are rapidly rising, the simple fact that it takes longer to recover from the infection than to die from it will also artificially inflate the death rate. Another factor is how early on each case is diagnosed. A country which is able to test larger numbers of people will be able to diagnose the disease earlier on, so there will be a greater lag between the recording of a diagnosis and the recording of a death; with cases doubling every 2 days, even a slight shift in this lag will have a large effect on the apparent death rate.

            Looking at closed cases, therefore, will only be meaningful for countries where either then numbers have reached a steady state (i.e. at the herd immunity stage) or where the outbreak has been controlled. So far that means China and S. Korea. Even then the numbers still depend on what proportion were actually diagnosed. For China we have a death rate of 4.5%, and for S. Korea it is just over 8%. But factoring in an unknown number of undiagnosed cases these are probably overestimates.

            The actual death rate, of course, depends very much on the age structure of the population, and would be expected to be higher in countries with a higher proportion of the elderly (such as Italy).

            What does all this tell us? That in the next few months the NHS will be overwhelmed and a lot of people are going to die (if 30 million get it and 3 – 4% die that is a million deaths in the UK). And we shouldn’t expect any vaccines to be available on this timescale.

            The media are running stories at the moment about the limited number of ventilators that will be available for those that need them. Interestingly, I had a long chat with a colleague yesterday who had just read a paper documenting what had happened to 1600 (or it might have been 1200) cases from two hospitals in China. Unfortunately I haven’t yet been able to find the reference, so I haven’t read it myself. Of those, 37 were ventilated, of which 36 died. So perhaps we shouldn’t be worrying about ventilators if they aren’t going to help very much (or perhaps they were leaving it far too late to start ventilating their patients).

            Our only hope, then, is if transmission can be slowed really substantially. It is not at all clear to me that in the more heavily affected European countries this is possible at all. China could manage it becuase the outbreak was confined to a single area, which they were able to isolate, and they still had the resources of the rest of the country to keep Wuhan and Hubei supplied with food and medical care.

            I’m not clear about what happened in S. Korea, though I believe that they managed to get on top of contact tracing very quickly, and made a database publically available showing where all the cases and their contacts had been. This was readily accessible via a smartphone app, which would tell people in real time which places near them they needed to avoid. Somehow I can’t imagine that working elsewhere.

            Hong Kong was ready for such an epidemic from the start, as they had already been badly affected by SARS. They immediately closed Disney World (which is on its own island) and set aside the hotels there for quarantine. The city itself closed down fairly quickly, and the outbreak never really took hold (Macau even more so).

            Unfortunately I don’t know where to find this level of detailed information about other countries. The Web site I linked to shows new cases per day for each country, and comparing these as a proportion of total cases for that country might give some idea of who is doing better or worse, but I would be wary of reading too much into these numbers without being able to see the graphs.

            “If we don’t listen to the modellers when we seek advice on how best to protect ourselves, as individuals and collectively, then who do we listen to?”
            to those guys who are setting the example of bringing down the numbers of fatalities during the pandemic; to those countries that demonstrate the success in dealing with the crisis. not to those who feel like running an exciting experiment that no other country adopts. do you not wonder why the UK is the only country that goes down this route? well, I do!

            On the basis of the data that I have been able to find, I am not at all clear who those guys are, or indeed whether they really are bringing down the fatalities as effectively as they would have us believe. Of course Government advisers have access to a lot more data than I have, and have the expertise to perform a much more sophisticated analysis, and I would certainly expect them to be examining the experience of other countries in great detail. But I don’t know how to judge the validity of what they come up with, or how it is interpreted by the Government.

            I am seriously wondering how the country is going to function if we really do go into full lock-down. How will we all get fed, and how many large and small businesses will go bankrupt? How many of us are going to end up in financial ruin? What state will we all be in afterwards? At least in Britain we are only panic-buying toilet paper and pasta, not combat knives and guns as in the USA.

            Maybe all the best strategy would be for the country to carry on as normal, and not to isolate people at all (except for those at highest risk). At least then the infrastructure wouldn’t fall apart. Maybe that is how Boris is thinking? I really don’t know.

            I know I am particularly vulnerable as I am immunocompromised to the extent that I am unable to produce any antibodies and I will have to rely on my NK (natural killer) cells if I contract this disease. Living with cancer for three years has made me realise that if I am going to die from Covid-19 I would rather it was next year than this year, and if this year, then I would at least like to enjoy the Summer first. So my wife and I are going to be staying in rural Wiltshire where at least we can walk the dog and watch the wildlife without worrying about encountering other people every time we go outdoors.

          • I hope you manage to stay virus-free [despite Johnson’s strategy]
            all the very best for your health
            edzard

          • @ JMK and EE,
            it is interesting to follow your „dispute“.
            You seem to have somewhat different opinions regarding the accuracy/usefulness of the COVID19 modelling approaches currently applied by the British Government.

            I have mixed thoughts about this issue.
            On the one hand, we are (according to most experts) just at the beginning of understanding a crucial factor that these models rely on: the biological characteristics of SARS-CoV-2.
            So I would certainly not have great confidence on the current models and prefer REAL data from the countries that were infected first – as much as this is possible.

            On the other hand: even if these models are not perfect, maybe such models can be useful to (try to) predict the best time to apply “social distancing” measures and the degree to which they should be applied.

            What I mean is:
            Based on “the experts”:
            *we cannot stop this virus from becoming endemic, so sooner or later, we will end up with a level of heard immunity (let´s say 70% of people infected).
            *we cannot keep a “full lock-down mode” until a vaccine is available without risking an economic disaster, especially since it is by no means certain that we will ever have a good vaccine.
            * there is a correlation between economic prosperity of a country and heath of the citizen, so we should try to limit the economic disaster to prevent subsequent collapse of social & health systems.

            From these assumptions, I wonder if it could be reasonable to use epidemiological models to
            *wait for a certain amount of time and “allow” the virus to spread, until it is foreseeable that the maximum capacity of the health system will soon be reached
            * then apply social distancing rules (again acc. to the best models) and try to keep infection rates at this high level until the herd immunity is reached.

            This could speed up arriving at the point of heard immunity (compared to applying drastic social distancing measures from the very beginning), while limiting the death toll and also the economic crises and the subsequent social costs.
            I wonder what you think about it.

            (@ JMK: I am aware that this “economy vs. disease” thoughts might sound hard-hearted or even cynical, especially since you belong to the high-risk group. Believe me, it is not meant this way. I just try to judge the problem as objectively as I can. All the best for you!).

          • my point was that there are too many assumptions hidden in these models to offer valuable predictions; therefore, the UK strategy runs an unacceptable risk.

          • Jashak,

            @ JMK: I am aware that this “economy vs. disease” thoughts might sound hard-hearted or even cynical, especially since you belong to the high-risk group. Believe me, it is not meant this way. I just try to judge the problem as objectively as I can. All the best for you!

            Thank-you for your kind words.

            I think my approach is much the same as yours, and indeed being objective about my own health has helped me cope with it. And you have to be objective in order to make wise choices.

            The rest of your post seems to me to be a good summary of what I think are the thought processes of our Government. Whether they are right or wrong remains to be proved.

          • Edzard,

            To quote from the article you linked to:

            What changed was new data on the impact of Italy’s out-of-control epidemic on its health service.

            Surely it is the right thing to change policy when new data become available? When I was working I used to reckon that if I was treating my prostate cancer patients the same way as the previous year it meant that I wasn’t keeping up with the latest research. In that sense the old protocols could be called “wrong”, but they were the best we had until new evidence came along.

            I honestly don’t know whether the Government’s policies will turn out to be right or wrong, though none of the other countries with similar sized outbreaks have managed to alter the doubling time of their case numbers so far (except China and South Korea, which I have discussed above), so perhaps it makes no difference to the infection rate what their policies are, in which case maybe they should be concentrating on limiting the damage to the infrastructure of the country instead.

          • i think the Italian data was available before

          • In case you haven´t see it already:
            a new modelling report has been released by the Imperial College.
            Quite frightening (if the underlying assumptions turn out to be correct).

            https://www.imperial.ac.uk/media/imperial-college/medicine/sph/ide/gida-fellowships/Imperial-College-COVID19-NPI-modelling-16-03-2020.pdf

          • thank you; i had seen it; good of you to post it

    • https://www.immunology.org/news/bsi-open-letter-government-sars-cov-2-outbreak-response

      do you agree that this at least partly vindicates my ‘irresponsible’ post?

      • Edzard,

        Yes it does, partly (see my longer reply). I certainly agree that the modelling data whould be made publically available for scrutiny, provided that those scrutinising it understand what they are doing.

        Julian

      • ” ….do you agree that this at least partly vindicates my ‘irresponsible’ post?”

        I am not sure if this is the way medical world functions! Or you?

        You quoted a figure: “Assuming a mortality rate of 1 – 2%, this means that Johnson is cheerfully accepting 400 000 – 800 000 fatalities.”

        How did you arrive at this figure? Why such large variation? What is the formula behind it?
        Each hypothesis/model is backed by an underlying mathematical formula and using data available, proves or disproves the model. (Adjusting the data to justify the model is another idea!)

        Data is now available. For some countries it is stabilized. Like Singapore or even Hubei province. Or may be the Cruise Liner stuck at Oakland.

        Hubei and the ship have been “hit on the chin”. The population, numbers infected and the one’s who don’t make it are known/will be known in a short while. The data updated in the formula would show the validity of the model.

        A check on Singapore data, qualified with the steps take by the Government there, will lay out steps required, with necessary modifications, for containing the problem in other areas.

        Reading the arguments put up by you and Dr Money Kyrle, I can only compare with information on the Spanish flu. Then also doctors were all at sea in their ability to take control. After 100 years, it is no different.

    • Dear Dr. Money-Kyrle,
      Quote:”For once I have to take issue with your uninformed and in my view irresponsible post.”
      __________________________________________________

      I value both, yours and Prof. Ernst opinions on the matter but do not understand which point exactly would justify such a harsh criticism. According to my information (e.g. from the news briefings from Prof. Wieler of the RKI and Prof. Drosten of the Charite and also from reading several of the most recent research articles about Corona in e.g. Nature and Science), EE comments seem to me both, informed and reasonable.

      Could you please point out which issues exactly you mean?
      I am really puzzled, because the numbers that you both accept (e.g. on herd immunity and potential fatalities) seem to be quite close.

  • Ernst, Dear fellow

    There was a wonderful discussion on BBC’s “this morning” (this morning): some young lady opined “we should all get this herd immunity”.

    I could not resist relaying this by SMS to a good friend of mine.
    By return he wrote, “I picked up a bottle of herd immunity from the chemist’s yesterday, so should be okay. . .”

    Sheer brilliance.

    I must head off to Boots tomorrow. Knowing my luck I bet they’ve sold out by now.

  • Am I the only one to find this REALLY confusing and, at least in part, contradicting what Johnson said?
    https://www.gov.uk/government/news/health-secretary-matt-hancocks-sunday-telegraph-op-ed

  • I’m glad to see the British government’s pronouncements on Covid19 being challenged. There is still an uncritical public attitude here towards authority, both towards government and the medical profession. After 20 years living in the Czech Republic I was taken aback in the UK to be automatically addressed by people less than half my age by my first name without offering theirs. The attitude of “doctor knows best regardless” goes hand in hand with this discourtesy. I am used to continental doctors explaining medical issues in depth, something of a rarity here. Boris and his expert advisors would be booed off the stage, say in France. They seem to say: we have this wonderful research but you wouldn’t understand it, so you’ll have to take it on trust. These days we can go back to original publications of research using the internet, particularly in the field of medicine. How can a basically theoretical exercise in the form of a simulation which is not open to public scrutiny be held up by our authorities as better than the bitter experience in the field of governments in the Far East, notably in China, on which the WHO and other governments base their policies on Covid19? Hitting the virus early and hard has worked in practice, anything else is unproven and highly risky.

  • Re the British government’s apparent change of gear, the previous protocols, for which we have seen no evidence, are just being buried. It is disputable that they were the best available. This is just a mantra which keeps being repeated. Dr Money-Kyrle seems to be suggesting that if we aren’t making headway against the epidemic, we should do nothing in order to preserve the economy. This is just a re-hash of the herd immunity argument. We have to give medicine priority over business, since by putting off the evil day, we risk a far worse economic collapse a couple of weeks on, a lesson that could be learned from China and Italy. Also we have a responsibility to the rest of the world. The WHO needs a coordinated response round the world where Covid19 is attacked simultaneously instead of one government after another going into denial then shortly afterward ringing the alarm bells. Otherwise once some countries have broken the back of the epidemic it will creep back from those that haven’t, and could go round over and over again like the plagues of the Middle Ages and antiquity. In the meantime we have to minimise the contact that permits contamination and test to the maximum so that spreaders are in isolation. With vulnerable patients self isolating, this two pronged attack, based on practice in the Far Eastis all we can do, since we don’t know enough about how this virus is spreading.

  • Dear E.E.

    This entire article is based on an erroneous assumption in the first sentence:>
    “Boris Johnson said we SHOULD take the coronavirus ‘on the chin’ and count on ‘herd-immunity’.

    The article goes on with:
    “… Johnson’s herd-immunity strategy”

    Boris actually said “COULD” …. before following the theorising with:
    “….But I think it would be better if we take all the measures that we can now to stop the peak of the disease being as difficult for the NHS as it might be.”

    So contrary to the mis-representation of lazy (or hostile ?) commentators, any “strategy” was the opposite of actively pursuing “herd immunity”.

    Separately Chief Science Officer Patrick Vallance talked about “herd immunity” – as a phenomenon that could occur either by design (vaccine) or by letting the virus take its natural course.

    So absent a vaccine, “herd immunity” to Covid-19 may occur naturally.
    Wher is the evidence that the Govt favoured a faster sprread over a slower spread ?

    • Yes – an interesting article in the Lancet.

      But it isn’t evidence of a deliberate strategy to encourage mass infection thus forcing speedy “herd immunity” on the population.

      I share the article’s puzzlement at insufficient testing.
      The idea that inbound travllers are still arriving with (apparently) no testing and no Landing Card (details of planned destinations) is bizarre.

      The disconnect between the centre – saying that there is enough equipment while the front line says not – is typical of an over-centralised government (officials mainly) operating from its Whitehall bubble.

      I understand that Army logistics has got involved – to get the equipment from storage to the front line – and has already started to deliver (apparently).

      But complaints of being underprepared seem very uncharitable – benefiting from hindsight.

      It’s one thing to make contingencies for (say) a surprise increase of something in the order of (say) 30%….
      …. but any politician or bureaucrat who proposed stockpiling for a vaguely possible 10 fold# increase in something would be accused of “waste”.

      #Made up for emphasis.

  • in the post i stated ‘i wish what the best solution is’; here is someone who might have it:
    https://www.nejm.org/doi/full/10.1056/NEJMe2007263?query=TOC

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