Scivillage.com Casual Discussion Science Forum

Some studies have shown that herd immunity could be achieved with as little as 20% infected.

And considering you can't justify why another lock down will work when the last obviously didn't, it seems you're the one just ignorantly parroting state TV, C2.

I think many people feel that a second lockdown would be improved, having learned from the mistakes of the first one? The first lockdown was total panic mode, but I would be open to testing out the herd immunity theory.

(Nov 20, 2020 09:18 PM)Syne Wrote: [ -> ]Some studies have shown that herd immunity could be achieved with as little as 20% infected.

So you would challenge State and/or Federal policy on the grounds of 'some studies' that you can't actually find right now. 
Just going with your 20% for the present - that would be 70 million infected. At 1% death rate that would be 700,000 deaths - is that OK with you to get the economy going again? We can go with your rather unfeasibly low herd immunity figure from a study you can't find - you want to go for an unfeasibly low death rate too? Think of a number. If you can't do the arithmetic I will be happy to do it for you.

As I recall you are the one valuing human life above all else - or not - this is your chance to show how much you really value a human life.

C2.

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(Nov 20, 2020 10:00 PM)Leigha Wrote: [ -> ]I think many people feel that a second lockdown would be improved, having learned from the mistakes of the first one? The first lockdown was total panic mode, but I would be open to testing out the herd immunity theory.

WHO Wrote:The percentage of people who need to have antibodies in order to achieve herd immunity against a particular disease varies with each disease. For example, herd immunity against measles requires about 95% of a population to be vaccinated. The remaining 5% will be protected by the fact that measles will not spread among those who are vaccinated. For polio, the threshold is about 80%.

Source WHO
https://www.who.int/news-room/q-a-detail...20to%20it.

Polio isn't particularly infectious and needs 80% immunity - so is Syne's 20% for a highly infectious virus real or fake? At a minimum of (say) 80% infected that would be 280 million Americans infected and at a 1% death rate that would be 2.8 million deaths. I'm not suggesting you shouldn't go for herd immunity - just be aware of what you are in favour of.

(Nov 20, 2020 06:46 PM)Syne Wrote: [ -> ]So...why didn't the previous lock downs work? If, as you say, "the virus thing would be pretty much over and done with" after a lock down, why didn't the last one do the trick?

Maybe because, as everyone expected, the virus mutated. It’s not the same strain that first emerged from China. A new study shows it has changed slightly in a way that makes it more contagious to humans.

In new experiments, animals infected with the new 614G strain passed it much more quickly to healthy animals than those infected with the original strain.

"Researchers at the University of Wisconsin in Madison infected 16 hamsters with the SARS-CoV-2 virus. Eight hamsters were infected with the new 614G strain. Eight others were infected with the original strain that was first identified in China. Each infected hamster was paired with a healthy hamster that was separated by a partition in a cage, so that the animals couldn’t touch but did breathe the same air. By the second day of the experiment, five of the eight healthy hamsters sharing air with animals infected with the 614G strain had fallen ill and were shedding the virus themselves, but none of the healthy hamsters paired with those infected with the original strain had gotten sick. The original strain did eventually sicken the healthy animals, but it took 2 more days for that to happen, proving that the changes helped to speed the spread of the virus."

Luckily, the antibodies from those that survived the first infections worked on the new strain, as well.

https://science.sciencemag.org/content/e...e8499.full

Edit:  Oh, I forget say that the new strain was found on mink farms in Denmark and the Netherlands and the minks have infected humans. When a virus mutates and is able to circulate through animal species, while keeping its ability to infect humans, it becomes way more difficult to eradicate. It would linger in the animal world until a new little susceptible (nonvaccinated child) came around. 

Denmark To Kill up To 17 Million Farmed Mink To Stop Coronavirus Mutation

(Nov 20, 2020 10:34 PM)confused2 Wrote: [ -> ]

(Nov 20, 2020 09:18 PM)Syne Wrote: [ -> ]Some studies have shown that herd immunity could be achieved with as little as 20% infected.

So you would challenge State and/or Federal policy on the grounds of 'some studies' that you can't actually find right now. 

Who said I couldn't find them? You're making an ass of yourself.

(Nov 21, 2020 12:53 AM)confused2 Wrote: [ -> ]

Syne Wrote:Some studies have shown that herd immunity could be achieved with as little as 20% infected.

I'm calling "Fake" on this - the WHO reckon 80% immunity for polio which isn't wildly infectious so 20% for Corvid 19 looks pretty darn fake to me.

You can call it what you like, but you don't seem to be looking. Just baby bird being spoon fed.

As severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads, the susceptible subpopulation declines causing the rate at which new infections occur to slow down. Variation in individual susceptibility or exposure to infection exacerbates this effect. Individuals that are more susceptible or more exposed tend to be infected and removed from the susceptible subpopulation earlier. This selective depletion of susceptibles intensifies the deceleration in incidence. Eventually, susceptible numbers become low enough to prevent epidemic growth or, in other words, the herd immunity threshold is reached. Here we fit epidemiological models with inbuilt distributions of susceptibility or exposure to SARS-CoV-2 outbreaks to estimate basic reproduction numbers (R0) alongside coefficients of individual variation (CV) and the effects of containment strategies. Herd immunity thresholds are then calculated as 1 − (1/R0)1/(1+CV2) or 1 − (1/R0)1/(1+2CV2), depending on whether variation is on susceptibility or exposure. Our inferences result in herd immunity thresholds around 10-20%, considerably lower than the minimum coverage needed to interrupt transmission by random vaccination, which for R0 higher than 2.5 is estimated above 60%.
https://www.medrxiv.org/content/10.1101/...20160762v3


Not only do people not mix randomly, infections (and subsequent immunity) do not happen randomly either, her team says. “More susceptible and more connected individuals have a higher propensity to be infected and thus are likely to become immune earlier. Due to this selective immunization by natural infection, heterogeneous populations require less infections to cross their herd immunity threshold,” they wrote.22 While most experts have taken the R0 for SARS-CoV-2 (generally estimated to be between 2 and 3) and concluded that at least 50% of people need to be immune before herd immunity is reached, Gomes and colleagues calculate the threshold at 10% to 20%.
https://www.bmj.com/content/370/bmj.m3563

So not only are there studies that estimate herd immunity for Covid at 20%, or less, the latter one also explains how populations less like Sweden (more diverse and more communicable among the susceptible) could more readily achieve herd immunity. The problem with the 50-80% infected for herd immunity is that they presume only a B-cell immune response, but studies have shown even a preexisting T-cell immunity:

Immune warriors known as T cells help us fight some viruses, but their importance for battling SARS-CoV-2, the virus that causes COVID-19, has been unclear. Now, two studies reveal infected people harbor T cells that target the virus—and may help them recover. Both studies also found some people never infected with SARS-CoV-2 have these cellular defenses, most likely because they were previously infected with other coronaviruses.

“This is encouraging data,” says virologist Angela Rasmussen of Columbia University. Although the studies don’t clarify whether people who clear a SARS-CoV-2 infection can ward off the virus in the future, both identified strong T cell responses to it, which “bodes well for the development of long-term protective immunity,” Rasmussen says. The findings could also help researchers create better vaccines.
https://www.sciencemag.org/news/2020/05/...m-immunity

So you might want to buy a clue before screaming "Fake" about stuff of which you're clearly and completely ignorant.

Quote:Just going with your 20% for the present - that would be 70 million infected. At 1% death rate that would be 700,000 deaths - is that OK with you to get the economy going again? We can go with your rather unfeasibly low herd immunity figure from a study you can't find - you want to go for an unfeasibly low death rate too? Think of a number. If you can't do the arithmetic I will be happy to do it for you.

As I recall you are the one valuing human life above all else - or not - this is your chance to show how much you really value a human life.

Okay with what no one knows we can stop? You seem awfully confident about something no one has demonstrated we even have the capacity to control. I get that your belief in our human ability to control things makes you feel safer, but it's, as yet, completely unfounded. Hell, even your forecasted deaths presume you know more about it than our current evidence can tell us.

Whereas there's little to no evidence that our effort can stop the deaths, and every indication that those policies are causing more deaths, it's a pretty utilitarian choice at this point...like it or not. I would much rather opt for nature being to blame than our reaction causing more needless deaths.

I value the human lives I know, for a fact, are being lost due to our actions. You're basically arguing that those lives are worth less than some hypothetical predictions.

Quote:Polio isn't particularly infectious and needs 80% immunity - so is Syne's 20% for a highly infectious virus real or fake? At a minimum of (say) 80% infected that would be 280 million Americans infected and at a 1% death rate that would be 2.8 million deaths. I'm not suggesting you shouldn't go for herd immunity - just be aware of what you are in favour of.

As shown above, it's precisely because polio wasn't particularly infectious that it didn't propagate quickly enough through susceptible sub-populations to establish herd immunity at a lower percentage.

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(Nov 21, 2020 01:36 AM)Secular Sanity Wrote: [ -> ]

(Nov 20, 2020 06:46 PM)Syne Wrote: [ -> ]So...why didn't the previous lock downs work? If, as you say, "the virus thing would be pretty much over and done with" after a lock down, why didn't the last one do the trick?

Maybe because, as everyone expected, the virus mutated. It’s not the same strain that first emerged from China. A new study shows it has changed slightly in a way that makes it more contagious to humans.

That doesn't answer the question. If it mutated since the first lock down, why wouldn't it simply mutate again after a second lock down? And wouldn't it becoming more infectious after the first lock down suggest that may have been a response to the first lock down itself? IOW, if possible hosts are less available, due to lock down, wouldn't it make sense that the virus would mutate to become more communicable...to take better advantage of fewer opportunities for new hosts?

Writing in August 2020 when cases in Sweden were declining there was (naturally) a search for an explanation. Looking at the figures for Sweden now  ( Nov 2020  https://epidemic-stats.com/coronavirus/sweden ) they're having a 'second wave' comparable to the first. The options would seem to be either a mutated virus or they were actually distancing perhaps not well but at least well enough.  There are many things that nobody knows but the current evidence suggests the hoped for herd immunity hasn't been achieved. Conclusions based on incomplete evidence can simply be wrong no matter how good they look at the time.

Quote:Buggert’s home country [Sweden] has been at the forefront of the herd immunity debate, with Sweden’s light touch strategy against the virus resulting in much scrutiny and scepticism.26 The epidemic in Sweden does seem to be declining, Buggert said in August. “We have much fewer cases right now. We have around 50 people hospitalised with covid-19 in a city of two million people.” At the peak of the epidemic there were thousands of cases. Something must have happened, said Buggert, particularly considering that social distancing was “always poorly followed, and it’s only become worse.”

^^^ from  BMJ  of 17th Sept 2020    https://www.bmj.com/content/370/bmj.m3563

Measles is highly infectious and the WHO suggest 95% vaccination to achieve herd immunity. In fairness vaccination doesn't give 100% immunity which will probably also be true of a Corvid 19 vaccination.

Syne Wrote:I value the human lives I know, for a fact, are being lost due to our actions. You're basically arguing that those lives are worth less than some hypothetical predictions.

I'm suggesting we should look at what is most likely to be true rather than what we would most like to be true - no matter how attractive the latter may seem.

(Nov 21, 2020 09:18 AM)Syne Wrote: [ -> ]That doesn't answer the question. If it mutated since the first lock down, why wouldn't it simply mutate again after a second lock down? And wouldn't it becoming more infectious after the first lock down suggest that may have been a response to the first lock down itself? IOW, if possible hosts are less available, due to lock down, wouldn't it make sense that the virus would mutate to become more communicable...to take better advantage of fewer opportunities for new hosts?

Yeah, possibly, by putting that selective pressure on it, natural selection would favor strains of the virus that transmit more easily.

It’s interesting because unlike DNA viruses, RNA viruses mutate rapidly because most of them lack a proofreading mechanism. In the beginning, I thought that might be an advantage because accumulated mutations could also weaken it, but this one is tricky though. Most RNA viruses don’t come equipped with a proofreading mechanism, but there are a few exceptions, such as Nidovirales, which the Coronavirus genus belongs to. They’re able to keep their genome intact. Unlike the influenza, they proofread their own genomes, which reduces the number of mutations.

That might be good news though because it might mean that a vaccine would remain effective for any future mutations. Like I said earlier, the antibodies from the old strain seemed to work for well the new strain.

What would be frightening is if it adapted to neutralizing antibodies. We’d be in big trouble then. The mink thing is troubling though. It makes it more difficult to predict and control.

What I find interesting is that the severe cases seem to mimic lupus. ACE2 autoantibodies have been reported in SLE patients and the ACE2 acts as a cellular doorway for COVID-19. I bet you that patients with more severe symptoms are producing ACE2 autoantibodies, as well as cytokines.

Will this vaccine prevent Covid once and for all time, or will annual shots be needed, like a flu shot? One of my coworkers heard that rumor (Covid vaccine being compared to a flu shot) but I can’t find any information online that confirms or denies that?

(Nov 21, 2020 07:40 PM)Leigha Wrote: [ -> ]Will this vaccine prevent Covid once and for all time, or will annual shots be needed, like a flu shot? One of my coworkers heard that rumor (Covid vaccine being compared to a flu shot) but I can’t find any information online that confirms or denies that?

Well, I’m just a laywoman, but from what I gather, no, it wouldn’t be like a flu shot that you need every year. It would more similar to the varicella vaccine. You’d probably need a booster shot every so often though.

(Nov 21, 2020 08:00 PM)Secular Sanity Wrote: [ -> ]

(Nov 21, 2020 07:40 PM)Leigha Wrote: [ -> ]Will this vaccine prevent Covid once and for all time, or will annual shots be needed, like a flu shot? One of my coworkers heard that rumor (Covid vaccine being compared to a flu shot) but I can’t find any information online that confirms or denies that?

Well, I’m just a laywoman, but from what I gather, no, it wouldn’t be like a flu shot that you need every year. It would more similar to the varicella vaccine. You’d probably need a booster shot every so often though.

Gotcha, good to know. Thanks, SS!