10 ms·

> This is another really great reason why the herd immunity threshold is lower than it has naively been claimed. It sounds like you're starting from the happy

> This is another really great reason why the herd immunity threshold is lower than it has naively been claimed. It sounds like you're starting from the happy assumption - herd immunity is much easier to achieve than we believe - and working backward to find data which justify your hope. To get good predictions, we have to be dispassionate and not assume the happy case. A realistic assessment would probably assign some sort of a probability range to different thresholds - a model might suggest there's a 60% chance the threshold is 60%, a 5% chance it is 40%, a 20% chance it is 80%, a 10% chance it is 90%. And any model has to take into account that any piece of data might be wrong, including this data about T-cell immunity.

modeless 6y ago
In my area, as in Sweden, cases have been declining for many weeks now. Lockdown didn't become stricter. People didn't become more compliant; rather the opposite. Why aren't cases skyrocketing the way they were a couple of months ago? What explanation is there other than the herd immunity thresholds being wrong?
- null_object 6y ago
  >What explanation is there other than the herd immunity thresholds being wrong? Just to give two possible alternative reasons: - outdoor life over the summer, leading to higher vitamin D levels; - older people are more likely to still be living in their summer cottages. Have you noticed that the death rate is possibly creeping upwards again? It’s simply too early to say. When I arrived back in Stockholm (from the countryside) three weeks ago, the town was very empty: our family was alone eating lunch in a central Italian restaurant on a Sunday. Now the streets are full again, but covid takes 3-4 weeks to take hold again. Not that I expect to see the levels of sickness from April again. But there’s a long winter still ahead of us.
- meddlepal 6y ago
  Mask compliance is reducing spread?
  - jtbayly 6y ago
    Sweden has recommended against wearing masks. So mask "compliance" would mean not wearing one, which should have led to an explosion of cases, no?
    - alkonaut 6y ago
      I’d say there has just not been a recommendation or mandate to wear them. There hasn’t been a recommendation against them. It could still happen they say, at least regionally e.g in public transport in one region for example.
  - deleted 6y ago
    [deleted]
  - nradov 6y ago
    A recent survey found only 6% mask compliance in Sweden so that's probably not a significant factor. There must be something else going on. https://www.telegraph.co.uk/travel/destinations/europe/sweden/articles/what-life-is-really-like-in-lockdown-hating-sweden/ https://www.telegraph.co.uk/travel/destinations/europe/swede...
    - johnisgood 6y ago
      Did they open schools there as well? Those increases seem to be around early September, around when in many countries with those enormous increases have opened their schools. Could it be this a significant factor?
      - Kiro 6y ago
        Yes, and schools were never fully closed.
  - modeless 6y ago
    I don't think our mask compliance has increased since the earlier spike; I would say the opposite. I don't have any hard data of course, so it's possible. I hope someone is collecting this data. If masks are truly effective enough to alone cause the dramatic change we're seeing, then the initial advice that they weren't necessary was utterly disastrous.
- joshuahedlund 6y ago
  Counterpoint is Madrid, Spain, which had one of the worst outbreaks in the spring (antibody tests showed prevalence of 11%[0], higher than Stockholm[1]) and now is having a severe outbreak again[2]. What explanation is there other than herd immunity not having been reached? As for Sweden, there's a lot of variety in human behavior and a lot we don't understand about the virus, and there are many possible explanations for the lack of major spread in any particular area. Sweden has continued to post a steady low level of cases over the last two months, not a continuing bell-curve decline, suggesting the virus is still consistently finding new hosts, just at a low and steady pace. [0] https://www.reuters.com/article/us-health-coronavirus-spain-idUSKBN22P1IK# https://www.reuters.com/article/us-health-coronavirus-spain-... [1] https://www.theguardian.com/world/2020/may/21/just-7-per-cent-of-stockholm-had-covid-19-antibodies-by-end-of-april-study-sweden-coronavirus https://www.theguardian.com/world/2020/may/21/just-7-per-cen... [2] https://medicalxpress.com/news/2020-09-doctors-hard-hit-madrid-motion.html https://medicalxpress.com/news/2020-09-doctors-hard-hit-madr...
  - jlmorton 6y ago
    The number you're citing for Stockholm is from April, well before the outbreak became severe in Sweden. Cases in Sweden continued to grow after that, and didn't peak until late June, when daily case counts were 3x higher than in April. (Although it's important to point out differences in testing - the positivity rate peaked April 20th - 26th). That's a different experience than Madrid, where the virus hit much earlier. By the end of April, daily case counts were 1/5th of their peak in Madrid. I'm not aware of a more recent study.
  - ArkVark 6y ago
    The simplest explanation for Madrid is that it locked down too early, and herd immunity (which seems to occur at about 20-25%, based on Antibody testing of New York and Sweden) was never reached. Lockdown also seems to increase the threshold for herd immunity and increase deaths, by dramatically changing the demographics of who is infected. Without lockdown, the youngest and most mobile people are likely to be infected - with minimal/zero deaths since COVID mortality is incredibly age dependent. Under lockdown, those people are at home and intermingling with family. The only 'social' activity is shopping for food, leading to an unnatural mingling of old and young. I live in Ukraine which has masks and little else against COVID. In shopping centers particularly in the evenings there are essentially zero old people - they fear for their lives, as they should. The most effective policy we could have adopted was 6AM-10AM public transport and shopping for the aged only, and everyone else from then on. Segregate the elderly population into the mornings and let the masses in in the afternoon. This might have required shifting school and work to later hours in the day for three months, which seems a minor inconvenience.
- soperj 6y ago
  more effective contact tracing.
  - Kiro 6y ago
    There's no official national contact tracing in Sweden. Every region does it differently and some not at all.
- rburhum 6y ago
  I got another data point that (potentially) supports your claim. Peru here. Highest death per million habitants in the world (not the numbers reported by the Ministry of Health that is artificially reducing the numbers). In Perú we are (sadly) keeping track of the pandemic by comparing the daily death count from previous years with the one for this years. You can safely assume: - there is no contact tracing - adherence to mask usage is good - social interactions are generally avoided with the usual folks that don't pay attention and an increase in those interactions every week. These are the "death curves" of every region: https://imgur.com/a/CWiUPiC https://imgur.com/a/CWiUPiC This is what happens when your government does not do anything and pretty much every one gets infected and your healthcare system collapses. You get a high spike in daily deaths and then a sharp drop (Lima is a special case for many reasons - size and geography). Heard Immunity in every region (except Lima - yet). Seroprevalence studies are on their way...
- deleted 6y ago
  [deleted]
- nend 6y ago
  That's not evidence of herd immunity thresholds being wrong though, that just opens up questions that need answers. Plus, the % positive rate doesn't seem to show a trend over the last 2 months, so I don't think your initial premise of "cases have been declining" is true. https://ourworldindata.org/coronavirus/country/sweden?country=~SWE https://ourworldindata.org/coronavirus/country/sweden?countr...
- ineedasername 6y ago
  Because social distancing is only one part of equation. Sweden has managed to address some of its other issues related to spread & fatalities. Notable among these are nursing homes, which had been a key source of spread. Once proper precautions were taken, they have stopped being as much of an issue. That said, Sweden isn't out of the woods: The current trends are flat at best, and perhaps have a slight upward cast to them for new infections over the past few weeks.
  - guenthert 6y ago
    > Notable among these are nursing homes, which had been a key source of spread. Because so many different people visit those? Nursing homes have been key source of death, but not of spread. Key source of spread are e.g. Prostitutes. Prostitution is (used to be) legal in e.g. Germany (afaik, in Sweden they intent to curb Prostitution by fining the client), but has been (temporarily) banned during the epidemic. That, of course, doesn't stop the custom, just moves it underground where the health of the providers cannot be monitored. Alleviating the financial problems of the providers might help curb the custom (as has been attempted in Germany afaik), as well as scaring the clients (as the state and media are doing their darnedest of).
    - ineedasername 6y ago
      Yes, nursing homes. Just look at the rates of health care workers in them getting sick. It spreads. Besides, I gave that as one single example that helps explain Sweden's infection trends. I wasn't trying to comprehensively enumerate the many steps Sweden has taken to address COVID-19 without strict shutdown. I gave an existence proof of the possibility that your claim of herd immunity isn't the only possible explanation. This is especially true given that other countries have not all had experiences in keeping with herd immunity. The fact is that we still know too little about this puzzle. But every time a new piece comes out, everyone rushed to jam that piece into their own pre-conceived ideas.
      - guenthert 6y ago
        > I gave an existence proof of the possibility that your claim of herd immunity isn't the only possible explanation. My what? What else did you read into my text which I didn't write?
- mbesto 6y ago
  > Lockdown didn't become stricter. People didn't become more compliant; rather the opposite. > What explanation is there other than the herd immunity thresholds being wrong? Let's start with sources on those first items before we get to an explanation. My general understanding is that Sweden recommended certain things but never technically enforced anything, so I'm not sure what "compliance" means.
  - modeless 6y ago
    https://www.google.com/covid19/mobility/ https://www.google.com/covid19/mobility/ says lockdown compliance has not changed much in my area and is trending slightly down if anything. I'm not aware of data on mask usage in my area, but a lack of confirmed scientific data shouldn't paralyze us; that results in problems like failing to recommend mask usage.
    - mbesto 6y ago
      > but a lack of confirmed scientific data shouldn't paralyze us Huh? That was not the point in contention. You said "the only conclusion is that the herd immunity numbers must be wrong" but have shown no evidence whatsoever to back that up.
      - modeless 6y ago
        You're putting words in my mouth; I did not say that at all. I asked "what explanation is there". I think a good discussion has resulted with some good points being made and some good data being shared.
- 13415 6y ago
  One possibility is that better air circulation in closed rooms due to open windows, higher vitamin D levels, and people meeting others outdoors rather than indoors more often have been contributing factors. These ameliorating factors would play less of a role in Southern countries like Spain or Italy, since they were already present in spring in those regions and so all infections took place in spite of them. Covid could be "lightly seasonal", so-to-say, though by far too infectious to be as seasonal as influenza. This is speculation, of course, unless it's backed up with studies. By the way, maybe I'm mistaken about this, but it seems to me that any increase of the number of immunized people will statistically decrease the R-value even long before herd-immunity is reached. Together with the measures and heightened awareness this might also explain the data.
- pier25 6y ago
  Maybe people in Sweden have less physical contact (hugs, etc) than in other countries?
  - beagle3 6y ago
    The joke says "Now that covid is less prevalent, scandinavians do not need to follow the 2m constraint .... and go back to their usual 5m"
- newacct583 6y ago
  Even taking this seriously: Sweden has seen 570 deaths per million so far. If that toll represents the transition to effective herd immunity, then we'd expect another 3-4 million people to die worldwide before this burns itself out. And... you think that's a good thing? Sweden's response has been a disaster any way you cut it.
  - henrikschroder 6y ago
    No. The age-stratified IFR is magnitudes different between people under 40 and people above 70. You can still achieve herd immunity without infecting the vulnerable. We have become better at treating patients with time as well, we now know that putting people on ventilators is a phenomenally bad idea, oxygen, steroids, and blood thinners is the way to go. Also, the death rate in the US is higher than in Sweden, so how are those lockdowns working out for you?
    - michaelmrose 6y ago
      The US population is unhealthy with bad health care on average. 42% are obese. It's not Lockdown leading to greater mortality.
    - hvac 6y ago
      The US? I'm not aware of any place here that's under lockdown.
      - henrikschroder 6y ago
        Oahu in Hawaii is currently under lockdown until September 23rd.
        hvac 6y ago
        Huh, you're right. Apparently there is limited hospital bed capacity on the Hawaiian islands.
      - username90 6y ago
- hanniabu 6y ago
  MY assumption would be that it's a combination of nice summer weather which makes social distancing easier, and all the super spreading idiots that don't comply are getting sick, recovering, and no longer able to (for the time being) continue to infect others.
- tw04 6y ago
  Without any details about "your area" it's impossible to say. We'd need the raw data, not your anecdotal "things are better".
  - Kiro 6y ago
    He's talking about Sweden as a whole. There's nothing anecdotal about it and the raw data is one Google search away. Sweden currently has one of the lowest death rates in Europe.
- FooBarWidget 6y ago
  In the Netherlands cases have been skyrocketing for weeks though.
tyingq 6y ago
The COVID "new cases" data for New York state seem to show something like herd immunity, despite numbers that should be well below herd immunity. I suppose it could be something else, like New York residents being more diligent about masks, social distance, etc. Anecdotally, though, that doesn't seem to be the case.
- ineedasername 6y ago
  NYC still seems like a ghost town to me.
- dasudasu 6y ago
  Could be something like people with behaviors consistent with a higher risk of catching/spreading it being already immune by now.
  - username90 6y ago
    That is a factor in herd immunity though.
- henrikschroder 6y ago
  Almost no one is wearing a mask in Sweden, and the current daily numbers look a lot like NY and NJ.
- Terretta 6y ago
  Partly NYC is relatively empty and relatively cautious since it was present and real, but partly it’s likely many times more folks have had it in NYC than has been widely reported, possibly one or two orders of magnitude more, leaving fewer candidates now. If, back in the spring, you worked backwards from NYC deaths using mortality rates within the lowest ranges in US studies, then it seemed likely that before summer infections may have already approached most of the population. Mortality rates of 0.5% would have a far higher number of infected, as noted in this April suggestion of much wider prevalence, which if the case ”the real number of infected people in LA County would be 28 to 55 times higher” — https://www.webmd.com/lung/news/20200424/more-data-bolsters-higher-covid-prevalence https://www.webmd.com/lung/news/20200424/more-data-bolsters-... Aside from that math, a variety of sources suggest perhaps 25% of New Yorkers infected in April, such as: A claim in June of ”roughly 25% by June” — https://www.cnbc.com/2020/06/30/roughly-25percent-of-new-york-city-has-probably-been-infected-with-coronavirus-dr-scott-gottlieb-says.html https://www.cnbc.com/2020/06/30/roughly-25percent-of-new-yor... A July claim (opinion piece, not an epidemiologist) of an even earlier peak, Feb and March: ”With a city population estimated by the Census Bureau at 8,336,817, the 22.7% prevalence from the late-April state survey would mean that nearly 1.9 million New Yorkers had already contracted the disease as of early April.” — https://www.bloomberg.com/opinion/articles/2020-07-23/new-york-city-s-covid-19-peak-likely-occurred-in-march-not-april https://www.bloomberg.com/opinion/articles/2020-07-23/new-yo... A July claim that ”over 60% of residents in some boroughs tested positive for the virus.”: https://abcnews.go.com/Health/nyc-neighborhoods-obtained-herd-immunity-study-suggests/story?id=71692365 https://abcnews.go.com/Health/nyc-neighborhoods-obtained-her...
zaroth 6y ago
There’s a naive equation for herd immunity which takes the unmitigated transmission rate or R0 of ~3 and calculates 1 - 1/R0 = .66. This is the upper limit on the threshold (what I call the “naive herd immunity rate”) assuming there are no unaccounted for effects which would otherwise reduce R0. Improved personal hygiene, social distancing, PPE, contact tracing, are all various behavioral ways that we have reduced the transmission rate below 2, which reduces the herd immunity needed to get transmission below 1 as long as those measures persist. Another way to say this is that if social measures get us to 1.3 then the infection still spreads until ~25% are infected. The natural immunity discussed in the article is effectively a free boost to your current herd immunity rate. If serological studies show 20% had been infected, but then you can add another 30% on top of that, you are effectively already at 50% herd immunity. I’m not sure what you mean by starting from a happy assumption. The real world data shows us that there is irrefutably something working to either reduce R0 or effectively boost the herd immunity level which isn’t showing up in the serological studies. TFA refers to several studies which show scientific evidence of a biological process that can explain what’s happening in the real world. We can accurately estimate the Rt by just looking at positivity rates, test count, and positive case count. Either R0 is much lower than initially calculated, or effective immunity level is higher than serology tests have shown. I suppose you can pick one, but Sweden at least is a strong datapoint that it’s a function of immunity not social suppression measures.

modeless 6y ago

In my area, as in Sweden, cases have been declining for many weeks now. Lockdown didn't become stricter. People didn't become more compliant; rather the opposite. Why aren't cases skyrocketing the way they were a couple of months ago? What explanation is there other than the herd immunity thresholds being wrong?

null_object 6y ago
>What explanation is there other than the herd immunity thresholds being wrong? Just to give two possible alternative reasons: - outdoor life over the summer, leading to higher vitamin D levels; - older people are more likely to still be living in their summer cottages. Have you noticed that the death rate is possibly creeping upwards again? It’s simply too early to say. When I arrived back in Stockholm (from the countryside) three weeks ago, the town was very empty: our family was alone eating lunch in a central Italian restaurant on a Sunday. Now the streets are full again, but covid takes 3-4 weeks to take hold again. Not that I expect to see the levels of sickness from April again. But there’s a long winter still ahead of us.
meddlepal 6y ago
Mask compliance is reducing spread?
- jtbayly 6y ago
  Sweden has recommended against wearing masks. So mask "compliance" would mean not wearing one, which should have led to an explosion of cases, no?
  - alkonaut 6y ago
    I’d say there has just not been a recommendation or mandate to wear them. There hasn’t been a recommendation against them. It could still happen they say, at least regionally e.g in public transport in one region for example.
- deleted 6y ago
  [deleted]
- nradov 6y ago
  A recent survey found only 6% mask compliance in Sweden so that's probably not a significant factor. There must be something else going on. https://www.telegraph.co.uk/travel/destinations/europe/sweden/articles/what-life-is-really-like-in-lockdown-hating-sweden/ https://www.telegraph.co.uk/travel/destinations/europe/swede...
  - johnisgood 6y ago
    Did they open schools there as well? Those increases seem to be around early September, around when in many countries with those enormous increases have opened their schools. Could it be this a significant factor?
    - Kiro 6y ago
      Yes, and schools were never fully closed.
- modeless 6y ago
  I don't think our mask compliance has increased since the earlier spike; I would say the opposite. I don't have any hard data of course, so it's possible. I hope someone is collecting this data. If masks are truly effective enough to alone cause the dramatic change we're seeing, then the initial advice that they weren't necessary was utterly disastrous.
joshuahedlund 6y ago
Counterpoint is Madrid, Spain, which had one of the worst outbreaks in the spring (antibody tests showed prevalence of 11%[0], higher than Stockholm[1]) and now is having a severe outbreak again[2]. What explanation is there other than herd immunity not having been reached? As for Sweden, there's a lot of variety in human behavior and a lot we don't understand about the virus, and there are many possible explanations for the lack of major spread in any particular area. Sweden has continued to post a steady low level of cases over the last two months, not a continuing bell-curve decline, suggesting the virus is still consistently finding new hosts, just at a low and steady pace. [0] https://www.reuters.com/article/us-health-coronavirus-spain-idUSKBN22P1IK# https://www.reuters.com/article/us-health-coronavirus-spain-... [1] https://www.theguardian.com/world/2020/may/21/just-7-per-cent-of-stockholm-had-covid-19-antibodies-by-end-of-april-study-sweden-coronavirus https://www.theguardian.com/world/2020/may/21/just-7-per-cen... [2] https://medicalxpress.com/news/2020-09-doctors-hard-hit-madrid-motion.html https://medicalxpress.com/news/2020-09-doctors-hard-hit-madr...
- jlmorton 6y ago
  The number you're citing for Stockholm is from April, well before the outbreak became severe in Sweden. Cases in Sweden continued to grow after that, and didn't peak until late June, when daily case counts were 3x higher than in April. (Although it's important to point out differences in testing - the positivity rate peaked April 20th - 26th). That's a different experience than Madrid, where the virus hit much earlier. By the end of April, daily case counts were 1/5th of their peak in Madrid. I'm not aware of a more recent study.
- ArkVark 6y ago
  The simplest explanation for Madrid is that it locked down too early, and herd immunity (which seems to occur at about 20-25%, based on Antibody testing of New York and Sweden) was never reached. Lockdown also seems to increase the threshold for herd immunity and increase deaths, by dramatically changing the demographics of who is infected. Without lockdown, the youngest and most mobile people are likely to be infected - with minimal/zero deaths since COVID mortality is incredibly age dependent. Under lockdown, those people are at home and intermingling with family. The only 'social' activity is shopping for food, leading to an unnatural mingling of old and young. I live in Ukraine which has masks and little else against COVID. In shopping centers particularly in the evenings there are essentially zero old people - they fear for their lives, as they should. The most effective policy we could have adopted was 6AM-10AM public transport and shopping for the aged only, and everyone else from then on. Segregate the elderly population into the mornings and let the masses in in the afternoon. This might have required shifting school and work to later hours in the day for three months, which seems a minor inconvenience.
soperj 6y ago
more effective contact tracing.
- Kiro 6y ago
  There's no official national contact tracing in Sweden. Every region does it differently and some not at all.
rburhum 6y ago
I got another data point that (potentially) supports your claim. Peru here. Highest death per million habitants in the world (not the numbers reported by the Ministry of Health that is artificially reducing the numbers). In Perú we are (sadly) keeping track of the pandemic by comparing the daily death count from previous years with the one for this years. You can safely assume: - there is no contact tracing - adherence to mask usage is good - social interactions are generally avoided with the usual folks that don't pay attention and an increase in those interactions every week. These are the "death curves" of every region: https://imgur.com/a/CWiUPiC https://imgur.com/a/CWiUPiC This is what happens when your government does not do anything and pretty much every one gets infected and your healthcare system collapses. You get a high spike in daily deaths and then a sharp drop (Lima is a special case for many reasons - size and geography). Heard Immunity in every region (except Lima - yet). Seroprevalence studies are on their way...
deleted 6y ago
[deleted]
nend 6y ago
That's not evidence of herd immunity thresholds being wrong though, that just opens up questions that need answers. Plus, the % positive rate doesn't seem to show a trend over the last 2 months, so I don't think your initial premise of "cases have been declining" is true. https://ourworldindata.org/coronavirus/country/sweden?country=~SWE https://ourworldindata.org/coronavirus/country/sweden?countr...
ineedasername 6y ago
Because social distancing is only one part of equation. Sweden has managed to address some of its other issues related to spread & fatalities. Notable among these are nursing homes, which had been a key source of spread. Once proper precautions were taken, they have stopped being as much of an issue. That said, Sweden isn't out of the woods: The current trends are flat at best, and perhaps have a slight upward cast to them for new infections over the past few weeks.
- guenthert 6y ago
  > Notable among these are nursing homes, which had been a key source of spread. Because so many different people visit those? Nursing homes have been key source of death, but not of spread. Key source of spread are e.g. Prostitutes. Prostitution is (used to be) legal in e.g. Germany (afaik, in Sweden they intent to curb Prostitution by fining the client), but has been (temporarily) banned during the epidemic. That, of course, doesn't stop the custom, just moves it underground where the health of the providers cannot be monitored. Alleviating the financial problems of the providers might help curb the custom (as has been attempted in Germany afaik), as well as scaring the clients (as the state and media are doing their darnedest of).
  - ineedasername 6y ago
    Yes, nursing homes. Just look at the rates of health care workers in them getting sick. It spreads. Besides, I gave that as one single example that helps explain Sweden's infection trends. I wasn't trying to comprehensively enumerate the many steps Sweden has taken to address COVID-19 without strict shutdown. I gave an existence proof of the possibility that your claim of herd immunity isn't the only possible explanation. This is especially true given that other countries have not all had experiences in keeping with herd immunity. The fact is that we still know too little about this puzzle. But every time a new piece comes out, everyone rushed to jam that piece into their own pre-conceived ideas.
    - guenthert 6y ago
      > I gave an existence proof of the possibility that your claim of herd immunity isn't the only possible explanation. My what? What else did you read into my text which I didn't write?
mbesto 6y ago
> Lockdown didn't become stricter. People didn't become more compliant; rather the opposite. > What explanation is there other than the herd immunity thresholds being wrong? Let's start with sources on those first items before we get to an explanation. My general understanding is that Sweden recommended certain things but never technically enforced anything, so I'm not sure what "compliance" means.
- modeless 6y ago
  https://www.google.com/covid19/mobility/ https://www.google.com/covid19/mobility/ says lockdown compliance has not changed much in my area and is trending slightly down if anything. I'm not aware of data on mask usage in my area, but a lack of confirmed scientific data shouldn't paralyze us; that results in problems like failing to recommend mask usage.
  - mbesto 6y ago
    > but a lack of confirmed scientific data shouldn't paralyze us Huh? That was not the point in contention. You said "the only conclusion is that the herd immunity numbers must be wrong" but have shown no evidence whatsoever to back that up.
    - modeless 6y ago
      You're putting words in my mouth; I did not say that at all. I asked "what explanation is there". I think a good discussion has resulted with some good points being made and some good data being shared.
13415 6y ago
One possibility is that better air circulation in closed rooms due to open windows, higher vitamin D levels, and people meeting others outdoors rather than indoors more often have been contributing factors. These ameliorating factors would play less of a role in Southern countries like Spain or Italy, since they were already present in spring in those regions and so all infections took place in spite of them. Covid could be "lightly seasonal", so-to-say, though by far too infectious to be as seasonal as influenza. This is speculation, of course, unless it's backed up with studies. By the way, maybe I'm mistaken about this, but it seems to me that any increase of the number of immunized people will statistically decrease the R-value even long before herd-immunity is reached. Together with the measures and heightened awareness this might also explain the data.
pier25 6y ago
Maybe people in Sweden have less physical contact (hugs, etc) than in other countries?
- beagle3 6y ago
  The joke says "Now that covid is less prevalent, scandinavians do not need to follow the 2m constraint .... and go back to their usual 5m"
newacct583 6y ago
Even taking this seriously: Sweden has seen 570 deaths per million so far. If that toll represents the transition to effective herd immunity, then we'd expect another 3-4 million people to die worldwide before this burns itself out. And... you think that's a good thing? Sweden's response has been a disaster any way you cut it.
- henrikschroder 6y ago
  No. The age-stratified IFR is magnitudes different between people under 40 and people above 70. You can still achieve herd immunity without infecting the vulnerable. We have become better at treating patients with time as well, we now know that putting people on ventilators is a phenomenally bad idea, oxygen, steroids, and blood thinners is the way to go. Also, the death rate in the US is higher than in Sweden, so how are those lockdowns working out for you?
  - michaelmrose 6y ago
    The US population is unhealthy with bad health care on average. 42% are obese. It's not Lockdown leading to greater mortality.
  - hvac 6y ago
    The US? I'm not aware of any place here that's under lockdown.
    - henrikschroder 6y ago
      Oahu in Hawaii is currently under lockdown until September 23rd.
      - hvac 6y ago
        Huh, you're right. Apparently there is limited hospital bed capacity on the Hawaiian islands.
    - username90 6y ago
hanniabu 6y ago
MY assumption would be that it's a combination of nice summer weather which makes social distancing easier, and all the super spreading idiots that don't comply are getting sick, recovering, and no longer able to (for the time being) continue to infect others.
tw04 6y ago
Without any details about "your area" it's impossible to say. We'd need the raw data, not your anecdotal "things are better".
- Kiro 6y ago
  He's talking about Sweden as a whole. There's nothing anecdotal about it and the raw data is one Google search away. Sweden currently has one of the lowest death rates in Europe.
FooBarWidget 6y ago
In the Netherlands cases have been skyrocketing for weeks though.

tyingq 6y ago

The COVID "new cases" data for New York state seem to show something like herd immunity, despite numbers that should be well below herd immunity. I suppose it could be something else, like New York residents being more diligent about masks, social distance, etc. Anecdotally, though, that doesn't seem to be the case.

ineedasername 6y ago
NYC still seems like a ghost town to me.
dasudasu 6y ago
Could be something like people with behaviors consistent with a higher risk of catching/spreading it being already immune by now.
- username90 6y ago
  That is a factor in herd immunity though.
henrikschroder 6y ago
Almost no one is wearing a mask in Sweden, and the current daily numbers look a lot like NY and NJ.
Terretta 6y ago
Partly NYC is relatively empty and relatively cautious since it was present and real, but partly it’s likely many times more folks have had it in NYC than has been widely reported, possibly one or two orders of magnitude more, leaving fewer candidates now. If, back in the spring, you worked backwards from NYC deaths using mortality rates within the lowest ranges in US studies, then it seemed likely that before summer infections may have already approached most of the population. Mortality rates of 0.5% would have a far higher number of infected, as noted in this April suggestion of much wider prevalence, which if the case ”the real number of infected people in LA County would be 28 to 55 times higher” — https://www.webmd.com/lung/news/20200424/more-data-bolsters-higher-covid-prevalence https://www.webmd.com/lung/news/20200424/more-data-bolsters-... Aside from that math, a variety of sources suggest perhaps 25% of New Yorkers infected in April, such as: A claim in June of ”roughly 25% by June” — https://www.cnbc.com/2020/06/30/roughly-25percent-of-new-york-city-has-probably-been-infected-with-coronavirus-dr-scott-gottlieb-says.html https://www.cnbc.com/2020/06/30/roughly-25percent-of-new-yor... A July claim (opinion piece, not an epidemiologist) of an even earlier peak, Feb and March: ”With a city population estimated by the Census Bureau at 8,336,817, the 22.7% prevalence from the late-April state survey would mean that nearly 1.9 million New Yorkers had already contracted the disease as of early April.” — https://www.bloomberg.com/opinion/articles/2020-07-23/new-york-city-s-covid-19-peak-likely-occurred-in-march-not-april https://www.bloomberg.com/opinion/articles/2020-07-23/new-yo... A July claim that ”over 60% of residents in some boroughs tested positive for the virus.”: https://abcnews.go.com/Health/nyc-neighborhoods-obtained-herd-immunity-study-suggests/story?id=71692365 https://abcnews.go.com/Health/nyc-neighborhoods-obtained-her...

zaroth 6y ago

There’s a naive equation for herd immunity which takes the unmitigated transmission rate or R0 of ~3 and calculates 1 - 1/R0 = .66. This is the upper limit on the threshold (what I call the “naive herd immunity rate”) assuming there are no unaccounted for effects which would otherwise reduce R0. Improved personal hygiene, social distancing, PPE, contact tracing, are all various behavioral ways that we have reduced the transmission rate below 2, which reduces the herd immunity needed to get transmission below 1 as long as those measures persist. Another way to say this is that if social measures get us to 1.3 then the infection still spreads until ~25% are infected. The natural immunity discussed in the article is effectively a free boost to your current herd immunity rate. If serological studies show 20% had been infected, but then you can add another 30% on top of that, you are effectively already at 50% herd immunity. I’m not sure what you mean by starting from a happy assumption. The real world data shows us that there is irrefutably something working to either reduce R0 or effectively boost the herd immunity level which isn’t showing up in the serological studies. TFA refers to several studies which show scientific evidence of a biological process that can explain what’s happening in the real world. We can accurately estimate the Rt by just looking at positivity rates, test count, and positive case count. Either R0 is much lower than initially calculated, or effective immunity level is higher than serology tests have shown. I suppose you can pick one, but Sweden at least is a strong datapoint that it’s a function of immunity not social suppression measures.