Covid strategies for Australia: herd immunity or quarantine land?

Let’s talk about some of the covid policy options facing Australia in the coming months and years. It seems to me we can either grasp the nettle and accept we will get a wave of highly visible covid-19 deaths before life returns to normal, or we can try and defend ourselves against any further wave and infections by quarantine rules, State border controls, immunity passports, tracer apps, and the like. The main cost of the latter is in the total collapse of several industries, as well as longer-term but less visible loss of life. The main political cost of the former is admitting we f*cked up first time round and needlessly damaged the economy and society for no benefit.

Let’s talk about the quarantine path first.

Stuck In Quarantine – Zombie Guide Magazine

If one only wanted to prevent a up flare of covid cases in Australia one should continue the current restrictions.

One would have strong quarantine rules regarding visitors from any country with a high number of active cases. Even with countries with few identified active cases, one would want a strict quarantine policy: there is a 2-week delay between the unseen spread of the virus via asymptomatic cases and visible deaths, so you don’t know whether a country is experiencing an unseen flare up of the virus. Hence even visitors from “clean” countries pose a risk. This means one should not expect too much of the idea of some large group of countries that declare themselves a covid-free zone and have free travel between them. One little wave of infections in one of them and such a system would already break down.

The economic costs of quarantine rules is that it kills off some of the tourism, a lot of the international student business, quite a bit of temporary migration, and most business travel. This is exactly why in the UK over 70 big travel operators and hotel businesses have called on the UK government to ditch its plans for quarantine rules. Those businesses are very afraid that the summer holiday season (mid June to August), in which they make a lot of their yearly revenue, is lost, so they are making a huge noise right now. It would mean the end of their business and hence the jobs they provide if the quarantine rules are kept in place. They claim to be close to 10% of the UK economy.

If you count all the ancillary business associated with tourism and business travel, like catering, this industry is somewhat similar in size in Australia. So quarantine rules come with a big economic impact, which is why right now the Gold Coast operators are strongly lobbying the Queensland government against border controls and quarantine rules. They claim 40,000 jobs are in danger. And the Gold Coast is just one small part of the Australian tourism and business travel industry.

And don’t forget, jobs and the economy are about lives. That’s why a job is called someone’s “livelihood”. Jobs support individuals and their families. As I have calculated before, a million jobs lost for just one year equates to over 100,000 life-years lost in terms of direct misery to the unemployed, and another couple of hundred thousand life-years via reduced public services and (health) consumption for the whole community.

Now, of course, things are not quite as bleak as saying quarantining arrivals from outside of Australia kills all tourism and hospitality: quarantine rules not only discourage foreign tourists from coming in, but they also discourage domestics from going out, meaning less foreign tourism but more domestic tourism. Australians do like to travel, with a million or so abroad at any moment in time and they’d do less of that if forced into quarantine every time they return from abroad. With the glut of Asian tourism in the last 10 years, Australia is probably a net winner in terms of the international tourism trade, but it clearly wont be true that its tourism industry will have no clients if the Asians and others are discouraged from coming via quarantine rules. Destinations popular with Australians might even see a net increase. It’s the internationally oriented tourism, travel, and hotel chains that will lose out most. So yes, jobs are on the line, but not quite as many as the whole of the industry.

That is unless one has lots of border controls within Australia that basically kill off most internal tourism as well! Lots of internal controls on movement are essentially equivalent to preventing lots of people from doing their jobs (ie, looking after interstate tourists and travelers), which is a straightforward reduction of total production in Australia. Its like a mandatory closure.

So there is an economic price tag on quarantines rules for foreign visitors and a separate but also big price tag on internal border controls.

Nevertheless, let us press on with describing what the continued suppression path could look like. Importantly, you wont keep this out completely with a quarantine regime, if only because of all those government and military people still flying around on official business. Also, you’ll get cases that fall through the cracks of any quarantine system, whether that is an infected visitor escaping from the quarantine hotel or some infected piece of clothing getting passed on from a docking freight ship. It’s just too contagious and hard to notice to keep out completely when you have a lot of activity in airports and freights (which you have even right this moment). So you cant only have a quarantine regime if you want to keep the virus repressed.

Another element in the suppression strategy is the notion of forced local lock downs connected to a track-and-trace system. They now announced such a system in the UK: anyone tested positive for covid will be asked to say whom they have been in contact with recently, and those others can be forced into an involuntary two week lock down to prevent further spread. The UK government is essentially copying the Chinese system of neighbourhood snitches for this, ie 25,000 busy-bodies whose job it will be to go and pester everyone about their health and their movements. Those 25,000 ‘contact tracers’ will be on the phone to all the friends of an identified case, as well as looking at the movements of a victim’s mobile phone, charged with looking at where an infected person might have gotten the virus from and whom he or she might have given it to.

To Tame Coronavirus, Mao-Style Social Control Blankets China - The ...One might call this a “low-tech” track-and-trace system, something that other countries try to do with apps but that China and Japan have done with an army of local busy-bodies checking on all others. Key in this system is that one can be forced to undergo a covid test if one the new busy-bodies think that is appropriate. One might thus call it the covid-police.

The Australian government first tried something like this with a mobile phone track-and-trace app, but that one now seems to be abandoned. Yet, it can try again with an updated app or copy China, Japan, and the UK, in setting up a covid-police to track and trace more manually.

Now, of course, the dangers for abuse in this system are horrendous. These contact tracers can threaten businesses with oblivion by calling for a local lock down of all the high-contact businesses in an area, and they can make life hell for any particular individual by calling all their friends and families, or forcing them into continuous tests. As a result, people will be very reluctant to have tests done!

Perhaps even more important is that “track-and-trace” creates its own demand when it is “successful”: by preventing local flare ups, such a system means the community never gets high infection levels and so perennially remains vulnerable to them. So one has to track and trace until there is a vaccine. And with a new virus or a new version of the covid-19 virus, one would have to have the track-and-trace system running again. The local Chinese busy-bodies also find some new threat to guarantee them an ongoing job, and the Australian covid-police would do so too. So its an ongoing cost and form of interference. Just like the Chinese system of social busy-bodies. It would turn the UK or Australia into a mini-China.

Successful continued repression in Australia comes with the irrelevance of immunity passports: those only make sense if you have had enough cases of people recovering from infections. That’s relevant for the UK, but not Australia.

Crowds - The opera house was deserted. The doors were closed. The ...Note also how difficult a track-and-trace system is to operate with lots of visitors and foreign tourists in a neighbourhood. A place like Buckingham Palace or the Sydney Opera House, with a continuous flow of buses full of foreign tourists feeding into cramped spaces, does not allow one to track and trace all the interactions between them and the locals.

So track-and-trace almost inevitably comes with further restrictions: no crowds in massed spaces and no mass tourism. The Opera House deserted.

What does a ban on mass gatherings kill off apart from certain forms of tourism? Well, it kills of all major sports, cultural, or even political events. No stadiums full of football fans or music lovers. No festivals. No Opera House performances with meaningful numbers of attendants. No sizeable political demonstrations. No election rallies. No park runs. No London or Sydney marathon. Probably no large full open office spaces.

So track-and-trace combined with bans on mass gatherings kills off a lot of joy and work. Again, this holds until there is a vaccine, and then applies again with the next version of the virus or some new threat.

Another policy meant to suppress the virus is social distancing and staying indoors. In Europe, we have basically woken up to its futility in preventing cases. Both the 1.5 metre ban and the pressure to stay indoors have now proven to be either largely useless (social distancing) or strongly counter-productive (staying inside). The Germans are thus leading the way in lifting the 1.5 metre ban, and governments are starting to realise they should encourage people to go outdoors.

The Australian government will be getting the same advice right about now.

However, one should note that whilst being in close proximity to others outdoors is now known to carry very little risk of infection, it is of course not the case that there are no infections from close proximity outdoors. Also, close proximity outdoors makes track-and-trace virtually impossible to do. If each individual is in close proximity to a thousand others every day, such as via public transport or lots of close passes on the streets, then the covid-police is going to have to call millions of people every day to inform them they have been ‘in contact’ with someone who has the virus. That is quickly going to become laughable. So there is a tension between letting go of the “stay inside and keep distance” policy and track-and-trace, which is basically why much of continental Europe has abandoned the idea of track-and-trace.

Note also that, once again, preventing mass gatherings might create its own demand if it is successful: one prevents lots of people from catching the virus so one maintains total vulnerability in the population.

Then, the business of face-masks. These have now been found to have a particular use in crowded indoor places with low humidity and poor ventilation. They are thus made compulsory in many European countries for use in public transport (which is crowded, poorly ventilated and sometimes with low humidity). They seem quite important in reducing infection rates.

For those not yet in the loop on the medical reason for this: the issue is tiny “respiratory” droplets of water and saliva (snot!) in the air which contain the virus and which people breathe in. Infected people breathe out rather a lot of such droplets and those droplets can hang in the air for hours depending on circumstances. Those circumstances are humidity and ventilation: if a place is well ventilated, the droplets move away or fall to the ground, and if there is high humidity the droplets also fall down much quicker. On the ground, those droplets are not much of an infection hazard. And where is ventilation good? Outdoors. Where is it bad? Indoors.

So this has become the new wisdom on covid-19 infections: the main place lots of people get strongly infected is in crowded indoor places with poor ventilation, like the Sydney Opera House on a dry day. Sit in there with a few infected people for a few hours and the infection will have reached all areas of the lungs, a much worse form of infection than having only the nose infected by a chance meeting outside. The face masks stop most of the droplets.

So compulsory face-masks in public transport come with another strongly suggested policy, which is continued bans of large gatherings in poorly ventilated indoor places, or at least compulsory face masks in those. That includes lots of school sports. It includes parliament, though they’ll be fixing the ventilation there as soon as they can. It includes bus rides full of tourists. It includes ocean cruises and large boats generally. It includes lots of factory floors. It includes academic conferences, business retreats, and all those other mass-indoor events. For some, you can imagine everyone wearing face-masks for an hour so, but for many, like factory floors or indoor sports, wearing continuous face-masks seems pretty infeasible.

So it kills off an awful lot of industries and activities, at least in the face-masks-off form we used to know, until there is a vaccine, which might well be never. Considering how every year there are new versions of the flu, that it normally takes many years to develop and test a vaccine, and that there is still no vaccine for the previous covid-virus (SARS), one shouldn’t believe in a quick vaccine miracle too easily.

Realistically speaking, the package of quarantine, State border controls, track-and-trace, face-masks, and banned mass gatherings should be expected to have to stay in place for several years in a suppression strategy. Precisely if they work, they have to be kept up till a vaccine because the population never develops immunity. So one kills off large economic sectors indefinitely.

Now, particular aspects of the potential package are more socially and economically costly than others. It is hard to know with the data at present, but I think that compulsory face-masks are probably the least costly of the package, unless they are mandated for all offices and factory floors. They main cost is more indirect in keeping up the fear. Social distancing is probably the most economically and socially expensive item in the potential package as it kills off most of office life and regular work. If mass gatherings include office floors, then keeping them outlawed costs close to that of social distancing. Quarantine is quite expensive, particularly economically, whilst track-and-trace on its own is probably more socially expensive than economically expensive.

 

Let’s then talk about two different options for grasping the nettle, ie accepting some form of herd immunity is the way to go, which comes with accepting a second wave of infections and deaths with a full opening up of the economy.

 

Measles, journalism and herd immunity / Data news / News / Home ...The technically easiest thing to do is to simply lift all government-mandated restrictions (state and federal), have some measures in place for the most vulnerable (unhealthy old people in nursing and retirement homes), and otherwise just watch and see what happens as international tourists, business people, migrants, and students come flooding back in. Like in Sweden, one would let individuals and businesses make their own calculations and decisions on how afraid they would be of what, but the official line would have to be that the risks in hindsight were much smaller than initially feared and people should hence just get on with their life and not be so scared.

There would clearly be a wave of infections and deaths lasting a few months. That wave would be quite a bit larger than the first wave Australia had. How large is not known, but I would personally expect it to be inbetween Sweden, which looks like ending up with a death rate equivalent to 15,000 Australians, and Japan, which would mean a few thousand Australians. Hand on heart, I’d expect about 10,000 covid deaths in Australia if we fully open up and stop worrying about the virus.

The advantage is that the economy starts to recover and social life resumes. There would still be one hell of a recession and a leftover government debt, but at least one would be on the path upwards again rather than killing off more industries permanently.

What happens after that first wave? The experience in Sweden is still the most instructive: the virus keeps “burning its way through the population” to the degree that that is natural with the economic and social reality in that country. Large parts of the healthy population eventually get the virus. After 2 months, the Swedish virologists now think, on the basis of anti-body immunity tests, that only about 20 to 25% of the population in the capital have had the virus (up from 7% in early April). The key unknown is whether lots of people (50%?) have prior immunity anyway due to some previous exposure of a related virus. If so, Sweden is close to herd immunity right now. Otherwise, they would still have a few more months of relatively high infections to go before so many are immune that the number of new cases become negligible. The former increasingly seems likely, ie that one only needs 20-30% of the population with anti-body immunity to have herd immunity. Part of the reason immunity is happening slower than expected in some countries is because of the high degree of voluntary isolation by a population afraid to gather in large numbers. In hindsight that was hence a big mistake and lots of damage could have been avoided letting them get exposed quicker.

Australia would be on a similar trajectory, with probably lower eventual levels of the population having been infected because Australia is more spread out, more humid, and might be lucky in importing less virulent versions of the disease than Sweden.

So it would take maybe 4-6 months for the number of cases to drop to almost nothing, after which you’d get the occasional local flare-up but no major further waves as a large part of the population has become immune. If it turns out that people lose immunity, you’d get smaller waves in subsequent years, much like the flu comes around every season. Eventually the population shrugs it off as just another health risk among many other, more worrying ones, like smoking or obesity.

Now, for me this represents the politically easiest option as one does not have to do anything radical but simply talk down the risks of the virus and give in to the demands of business to lift restrictions.

The narrative writes itself: “we have to make a living”, “we cant hide away from the world”, “Australia must be open for business”, “The virus is not even 1/10th of the risk of smoking”, “Our children must have a future”, “our elderly must be allowed to mingle with their family and friends”, “we cannot police the whole population”, etc.

This is the politically easier option and thus the more likely one. Yet, if one is of a more pro-forward and maverick nature, like myself, one is interested in the question of the smartest option around. What would that look like?

I think the smartest option around is to have a designated period in which one tells the old and frail to stay away from the active part of the population, whilst one deliberately created herd immunity by letting the healthy who come most into contact with others get a mild infection in the nose. You’d literally give them nose-sprays with the virus, a technology we already have and could mass-produce quickly.

One would thus have an infection program to catch up with Sweden, but then with fewer deaths and less economic disruption. You’d want something like 30-40% of the population to get infected, and that of course should be the most active group that runs almost no risk of dying from the infection. That’s 18-60 year olds who travel around a lot, which includes public transport commutes.

So you have a second wave, but one that is created and managed rather than one that occurs naturally. One can repeat the exercise in future years if it turns out that people lose immunity. There would of course still be a sizeable number of deaths from this approach. Not so much among those deliberately infected, but among those infected by the deliberately infected. One would try to minimise this damage, but one cant prevent such a large group of people entirely from working or mingling during their infectious period and one should thus expect to fail to some degree in completely protecting the vulnerable population during this deliberately created second wave.

Is this the lowest risk option? I think on balance yes, but it is not without risk. One such risk is that one didn’t need to do it because of some as yet unknown advantage that Australia might have that would make the natural “herd immunity level” particularly low. In that case the “second wave one needs to have to get back to normal” could be much smaller than it seems at present. Just as the fatality of the virus was totally over-estimated, so might the level of the population needed to be immune to get herd immunity also be over-estimated.

One indication that this might be possible is that much of Asia and Africa simply has incredibly low infection and death rates of this virus, suggesting that “doing pretty much nothing” would not lead to much death or infection in those places anyway. Just like malaria does not exist in Europe because it is too cold, maybe covid-19 has a tougher time in Australia than you’d think from merely looking at the usual indicators (urban density, climate, health characteristics of the population, age structure, work habits, social habits, etc.). So the deliberate infection options comes with the risk of creating a larger second wave than you’d actually need.

Politically, the fast-track policy to herd immunity also seems a tough sell. It is super easy to criticise and you’d have a conga line of supposed experts warning of the dangers of doing this. Whilst there are the odd medics whispering in the corridors about such an option, there is not an open consensus on it, so one cant hide behind some recognised solidly large group of scientists. You’d get doctors grand-standing how deliberate infections violate their oaths, and lots of other forms of protest. That alone would seem to make it a political impossibility, even though it seems to me the smartest option on the table with the least net economic and social disruption. Its probably too toxic for politicians to even mention it.

 

Between A Rock And A Hard Place. Stock Photo, Picture And Royalty ...These are then the more politically realistic options: continue with suppression indefinitely at high social and economic cost until the miracle vaccine appears, or open up fully and take your chances. Whilst Australia is currently right on track with the suppression option, it seems inevitable to me it will end up with laisser-faire after a few months of pussy-footing and continued economic harm. It would be nice to visit Australia again without needing to spend 2 weeks in a hotel room alone.

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16 Responses to Covid strategies for Australia: herd immunity or quarantine land?

  1. David Harris says:

    Bravo! I am upset by the way that people (especially politicians) believe that man-made laws can get around the laws of nature. The virus will do what viruses do.
    Nature implements its law of survival of the fittest through a system of predators and prey. The role of predators is to strengthen and improve the prey population by removing the less useful (slow, old, weak, careless) leaving the fittest in the population. Covid19 is just such a predator, favouring a strong immune system. Those who recover from infection do so because their own immune system eliminates it. A vaccine doesn’t stop or kill the virus – it just makes the immune system recognise it more quickly. I like your logical approach, but in the end, what will happen is what nature will allow.

    • paul frijters says:

      thanks.

      I do want to push back on this “what Nature will allow” business. We are also part of Nature and using our natural wits to minimize the damage the rest of Nature can do us whilst maximising our own interests always seemed very sensible to me. Natural even. It is, after all, the Anthropocene.

      So I am not someone who in principle says we should let Nature take its course. Its only when that’s the best option available according to our own criteria that we should say that. Long live the Anthropocene.

  2. Aaron says:

    What about a covid test instead of a 14 day quarantine? Countries like Iceland and Antigua are proposing that. I think it would have to be taken before you board the plane to Iceland or wherever.

    • paul frijters says:

      that would be a lot less disruptive, that’s for sure. There would probably be many tourists, students, and business people willing to put up with that.

      One big problem though is that it takes something like 24 to 48 hours to get the result from the test. So forget about last-minute flights then or anyone not organised enough to get to a test centre 48 hours before flying.

      Relatedly, one can easily cheat the test, particularly with such a long delay. And one can get the virus after testing and before boarding.

      Also, tests have false positives and false negatives. Not many (1%) but that’s way too much if you want to keep a virus out.

      Finally, this thing is very dormant and hardly noticeable in many people when they have it, and it can be present in different parts of the body. So a nose-swab doesnt pick up those who have it in their lungs (someone correct me if this isnt true!). The amounts might be too low to pick up, especially at the start, a major issue for the healthy asymptomatic cases who are the super-spreaders because they dont know they have it.

      So I do understand why Australia is not keen on this. The anti-body tests are even worse. Anti-body levels only start to increase quite a while after one has picked this thing up. So then the delay is a month.

      • Aaron says:

        IMO, quarantines will never be enacted because they’re so expensive and impractical – like you said, it kills off most international travel. But, people will put up with the testing and have to plan in advance for their trip. It’s going to become a totally unnecessary tax that will get applied to every traveler, but Australia has to do this to show they are being responsible. Even if one or two countries start opening with such testing, they’ll be forced to copy them. It seems the world is headed in this direction.

        The point of test cheating and false negatives remains and for this reason, I think we’ll have social distancing and testing/tracing in addition to the testing. It also looks like certain things are gone for years, maybe even permanently (any big social gathering basically), until we have a vaccine. Trying to stay “covid free” allows for no error. Sadly it appears people have accepted it. Travel bubbles are forming already. The world we are heading towards sounds pretty horrible to me, yet I feel powerless to change it.

        I don’t know what happens to countries like Sweden and the US, and many others including poor countries. They will almost certainly try to mimic to show they are making an effort, but it’s hard to say where it will end up.

        • paul frijters says:

          hard to foretell the dynamics, indeed, but I am less pessimistic than you. It is not that I trust in reason, but I do trust in the great pull of greed. And making ongoing economic losses whist other countries are lapping up the tourism, students, tax evading businessmen, and other goodies that you get with a more relaxed approach are powerful drivers.

          It’s an empirical question though. We will learn the outcome of this one!

          • Aaron says:

            I hope you are right. I derive my optimism from the reality of countries that simply cannot pull off any of this nonsense, either because they are too crowded (developing countries) or too disorganized (like the US).

          • David Harris says:

            Perhaps we should define more clearly the problem we are trying to solve. This seems to me to be something like “Reduce the adverse effects of Covid 19 on the community. These adverse effects appear to be serious illness and death in a small number of those affected. The number per capita is small, but combined with the seriousness of the possible illness, is enough to cause a large number of deaths and to overwhelm our medical system.”

            For a very large number of those affected, catching Covid19 is no big deal. So, the solution for the problem must address the suffering of the small number of seriously affected. Their suffering must be reduced enough to greatly reduce the death rate and greatly reduce the need for their hospitalisation. So, Covid19 is in the community, but with less deaths and less strain on the health system.

            This can be compared with AIDS. No vaccine, but enough new medical treatments to keep those with the virus alive, out of hospital and able to live a normal life. Yes, I know this is a stretched comparison but the principle is there, and many medical treatments are currently under development to do the same for Covid19.

            And, all the while, the virus is doing its thing, 24/7 – infecting, spreading, mutating.

            We can keep Covid19 under control at huge cost. This cost will eventually be unbearable, as is beginning to happen in Australia. Life will not go back to ‘normal’ because the new ‘normal’ will have Covid19 as a component which cannot be ignored.

            As you say, Paul, it is hard to foretell the dynamics. I’d love to come back in 20 years, or 50 years, to see what happened. But I am an octogenarian…

  3. Bruce Bradbury says:

    Would the economy recover if we adopted the Swedish model? Compared to the current situation, we would have many _more_ people seeking shelter, and international travel would remain low.

  4. Margaret Hogge, Non-Smokers' Movement of Australia Inc. says:

    Exit strategy: We can do it for COVID-19, why not tobacco? (online Insight article, 18 May 2020).

    Two Australian experts in Tobacco Control, Emeritus Professor Mike Daube and Professor Rob Moodie discuss the smoking pandemic which takes 20,000 Australian lives each year.
    We have known for 70 years, since May 1950, that smoking causes lung cancer.
    Quote “ We know the cause, the harms, the vector and the comprehensive public health approach recommended to bring it to an end”.

    This Sunday, World No Tobacco Day 31 May, we call on every Australian politician to pull out all the stops and work together to end this carnage.

    A comprehensive public health approach towards a Tobacco End-Game would include a Tobacco-Free Generation, where nobody could legally purchase if born after a certain date; heavy penalties for “social-supply” to friends and family; smoke-free, clean-air policies protecting everybody, in vehicles and (horror of horrors) in the home, from the toxins in second-hand tobacco smoke; indoors everywhere, including in shonky 75% enclosed/ legally unenclosed gaming rooms; as well as outdoors near others; vastly increased funding to promote quitting programs to assist the 90% of Australia’s 2,500,000 smokers who want to escape their addiction; free quitting advice and pharmacotherapies; purchasing from specialist licensed tobacco-sellers only (not at every corner shop, supermarket, newsagent, petrol station); individualised smoker’s licence, similar to a prescription – see Prof. Simon Chapman’s incentive concept on YouTube; pursuing Big Tobacco in court to recover damages, currently costing Australia $137 billion annually. There’s a start.
    Collateral benefit: no smoking in vehicles will lead to less cigarette-butt tossing, thus potentially less bushfires. Climate change causes enough disasters.

  5. Tony says:

    After 2 months, the Swedish virologists think only about 20 to 25% of the population in the capital have had the virus, and they thus still have a few more months of relatively high infections to go before so many (50%?) are immune that the number of new cases become negligible.

    There is recent data (week 18 of the year, so up to the 5th of May I think) that 7.3% of people in Stockholm have antibodies and maybe 5% of Sweden in total see here. I.e. 5% in the three months since their first infection.

    It is difficult to calculate when herd immunity can be reached. However, there is a really nice ABC new article about the reproduction number, see here. If you look at the graphs on the link everywhere has a basic reproduction rate of about 1.0. I.e. the number of new cases today is similar to yesterday’s. In the case of places like Sweden, perhaps only a few tens of thousands of people are infected at any one time. Potentially you could take a few years to infect enough people.

    As we discussed on another thread, it seems many people (30-60%) have some limited, pre-existing immunity due to common cold coronaviruses, on the other hand immunity to those same viruses wanes after about a year. So, really if you want to infect lots of people, you have to push for lots of infections, sick people still going to work, import lots of cases indefinitely. However, the behavioural evidence suggests that as infections rise, people will take action to avoid infection. In effect that is an uphill battle to achieve that behaviour.

    • paul frijters says:

      Hi Tony,

      I think the issue of pre-existing immunity is really important but of course one I will have to leave to the virologists to figure out. It makes it hard to estimate just how many are immune in a community.
      Yet, I think its very unlikely the pre-existing immunity is anywhere near as large as 30% or higher. That’s because of the recent data on anti-bodies in New York. They have found whole neighbourhoods (basically in some of the more deprived black-American neighbourhoods) that have about a 50% rate of the population with anti-bodies. That suggests i) that they cannot have had much pre-existing immunity at all, including the common cold which in a place like New York must be a very normal illness (the place is cold and windy), ii) you need something like 50% for herd immunity at least in a crowded place like New York, and iii) it can be done to actually have so many of the community infected in a short period of time.

      Now, on the Swedish data, which I talked about in a previous post, the crucial point is that that data comes from mid-April and their virologist claim there is about a two week lag between getting the disease and seeing anti-bodies. So they reckon the 7% was early April and that if you consider the evolution of the known cases, they must be up to 20 to 25% now. This is also why I said that this is what the swedish medics said, not what a study had shown! Still, its a lot less than the numbers claimed earlier by that Swedish ambassador, presumably informed by the earlier modeling of the same Swedish medics. https://clubtroppo.com.au/2020/05/14/on-corona-covid-19-herd-immunity-and-wellby-tradeoffs-key-predictions-and-numbers/

      The issue of behaviour indeed makes it tougher to catch up with Sweden, but that is largely a matter of fear and I see no problem in offering money to those willing to get infected. And one can make it a condition for certain forms of travel and that sort of stuff. But I just cant see politicians going anywhere near such a thing. Maybe if other countries try it first.

  6. George Wilson says:

    Paul,
    You might benefit from spending some time listening/watching Nassim Taleb and Yaneer Bar Yam
    https://www.endcoronavirus.org/videos

    • paul frijters says:

      I gave this the benefit of the doubt and watched 4 videos. What can I say? Very unimpressive. They can’t see the forest from the trees. Only useful when/if I want to make the argument of how much mainstream scientist nowadays lack training in the relative magnitude and importance of things.
      Paul

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