Stunning Effectiveness of the Covid Vaccines

In summary, data from a recent article and study show that the claims of 99.9% of COVID-19 cases being mild are inaccurate. In fact, hospitalizations and deaths in those who are vaccinated are extremely low at 0.0007% and 0.0001%, respectively. This highlights the importance of keeping these figures in mind when discussing vaccinations with others. Furthermore, it has been found that the Pfizer vaccine's effectiveness can drop to 83.7% within four to six months after receiving the second dose, indicating a potential need for booster shots in the future. However, the vaccine remains highly efficacious and has a favorable safety profile.
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I have mentioned it in passing before, but I reread it in a recent article, so thought I would post it for reference:
https://medicalxpress.com/news/2021-05-tiny-vaccine-breakthrough-covid-cases.html

In those vaccinated .0007% hospitalisations and .0001% deaths. Please keep these figures in mind when discussing vaccinations with others. And we have known for a long time the claims like 99.9% of cases are mild are wrong eg from over a year ago:
https://www.thejournal.ie/debunked-survival-rates-5103495-May2020/

This sounds corny, but science was tested and found not wanting.

Thanks
Bill
 
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  • #2
bhobba said:
And we have known for a long time the claims like 99.9% of cases are mild are wrong eg from over a year ago

How seriously should we "debunk the internet". I read on the internet that the Queen of England is an alient who can only maintain human form by drinking human blood. How much effort should we put into debunking that?

99.9% does not need extensive debunking: (1-99.9%) of the US population is 330K, which would be an absolute maximum of serious cases if this is true. The data for deaths - hard to get more serious than that - is 1.8x that. Done.

In fact, surveys show that the public thinks Covid is substantially more dangerous than it actually is, particularly among the non-elderly. How much effort should go into debunking that?
 
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  • #3
bhobba said:
I have mentioned it in passing before, but I reread it in a recent article, so thought I would post it for reference:
https://medicalxpress.com/news/2021-05-tiny-vaccine-breakthrough-covid-cases.html

In those vaccinated .0007% hospitalisations and .0001% deaths. Please keep these figures in mind when discussing vaccinations with others. And we have known for a long time the claims like 99.9% of cases are mild are wrong eg from over a year ago:
https://www.thejournal.ie/debunked-survival-rates-5103495-May2020/

This sounds corny, but science was tested and found not wanting.

Thanks
Bill
Cases have hit 7500 in a 24 hour period in the UK as numbers continue to rise.

Majority in hospital are unvaccinated but I do not have the study, just the article

https://www.dailypost.co.uk/news/no...covid-patients-hospital-unvaccinated-20740518
 
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I saw an interview these days which went along the following lines:

"How long, do you think, would it take to get a regular admission for an mRNA vaccine?"
"I wouldn't even call it a vaccine. It is a completely new process where people's own immune system is used."
"How long!"
"Eight to twelve years is a reasonable assumption."

Thank god there are emergency admissions and BionTech and Pfizer took their chance! I don't know what would have been more devastating: a 10-year full-blown pandemic, or a 10-year lockdown. And to all who like to demonish "Big Pharma": BionTech was basically run by literally a Bulgarian couple of scientists in Germany. Imagine their production rates without Pfizer. And some competitors have or had serious trouble with purity in their production process. We may discuss costs and prizes, but we cannot discuss size.
 
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fresh_42 said:
"Eight to twelve years is a reasonable assumption."
If true, and it does seem reasonable, the real issue seems to be the new strains. I think Australia is on the right track in trying to develop a universal vaccine and local manufacturing of mRNA vaccines:
https://www.monash.edu/news/articles/monash-receives-$5m-grant-for-covid-19-mrna-vaccine

It really does look like the future of vaccines. But it will be a competition between competing technologies like Novavax.

Thanks
Bill
 
  • #6
bhobba said:
I have mentioned it in passing before, but I reread it in a recent article, so thought I would post it for reference:
https://medicalxpress.com/news/2021-05-tiny-vaccine-breakthrough-covid-cases.html

In those vaccinated .0007% hospitalisations and .0001% deaths. Please keep these figures in mind when discussing vaccinations with others. And we have known for a long time the claims like 99.9% of cases are mild are wrong eg from over a year ago:
https://www.thejournal.ie/debunked-survival-rates-5103495-May2020/

This sounds corny, but science was tested and found not wanting.

Thanks
Bill
One question I have: The people who get vaccinated are also the ones who take COVID-19 seriously, and so they social distance more and wear masks more. Would that not also contribute?
 
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Grasshopper said:
One question I have: The people who get vaccinated are also the ones who take COVID-19 seriously, and so they social distance more and wear masks more. Would that not also contribute?
Almost certainly.
 
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  • #8
Grasshopper said:
One question I have: The people who get vaccinated are also the ones who take COVID-19 seriously, and so they social distance more and wear masks more. Would that not also contribute?
but people more vulnerable to COVID - the elderly, diabetics, other health conditions - are also more likely to have been vaccinated. The selection bias can go either way
 
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  • #9
As the above shows, the issue is complex. I will be doing a post about Sydney and a report by the Actuarial Society of South Africa on lockdowns.
 
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The effectiveness of Pfizer’s COVID-19 shot can drop to 83.7% within four to six months after getting the second dose of its vaccine. This is the latest indication that vaccine-induced immunity to the virus can wane and some kind of boost may be necessary in the future.
https://www.marketwatch.com/story/p...ng-the-company-case-for-a-booster-11627579817
New research published Wednesday as a preprint indicates that the Pfizer Inc. shot provides 96.2% protection for the first two months, 90.1% effectiveness between the second and fourth months, and between 83.7% of protection for the fourth, fifth, and six months.

“We will need a booster eight to 12 months from the second dose,” Pfizer CEO Albert Bourla said Wednesday, according to a FactSet transcript of the company’s second-quarter earnings call.
Moderna Inc., which developed the other FDA-authorized mRNA-based COVID-19 vaccine, is also testing booster shots in clinical trials. It has been much quieter in its communication around a third shot.

Six Month Safety and Efficacy of the BNT162b2 mRNA COVID-19 Vaccine
https://www.medrxiv.org/content/10.1101/2021.07.28.21261159v1.full.pdf
ABSTRACT Background: BNT162b2 is a lipid nanoparticle-formulated, nucleoside-modified RNA vaccine encoding a prefusion-stabilized, membrane-anchored SARS-CoV-2 full-length spike protein. BNT162b2 is highly efficacious against COVID-19 and is currently authorized for emergency use or conditional approval worldwide. At the time of authorization, data beyond 2 months post-vaccination were unavailable.

Conclusion: With up to 6 months of follow-up and despite a gradually declining trend in vaccine efficacy, BNT162b2 had a favorable safety profile and was highly efficacious in preventing COVID-19. (ClinicalTrials.gov number, NCT04368728)
 
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  • #11
In Iceland, 96% of females and 90% of males 16 years or older have received at least one dose of a Covid-19 vaccine. Its vaccination rate, one of the highest in the world, makes it a particularly interesting place to look at the incidence and severity of breakthrough infections.
https://qz.com/2044284/icelands-rising-covid-19-cases-demonstrate-vaccine-efficacy/

Since the pandemic began, there have been 8,738 infections and 30 coronavirus-related deaths reported in Iceland. The country managed to control the virus relatively well and has reported only one death in 2021, on May 25.
Population of Iceland 356,991 est (2019); the population of the least populous US state, Wyoming, is 578,759 (2019). Wyoming has had 66,453 Covid-19 cases and 786 deaths. Another small US state, Vermont, has a population of 623,989 (2019); Vermont has had 25,320 Covid-19 cases and 260 deaths.
That there are hardly any deaths accompanying the rising case count is a good sign. The data show that vaccinated people who are getting the virus are generally recovering without serious illness.
Population and Covid number from Google, except for the Iceland numbers stated from the QZ article.
 
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Yes, Iceland is a warning to us all. With the Delta varient and high vaccination rates, we will certainly prevent severe disease, hospitalisation and death. But even an asymptomatic case can get long Covid:
https://www.pharmacytimes.com/view/...ts-were-asymptomatic-during-initial-infection

And long Covid may be more common than the general public thinks:
https://theconversation.com/the-mys...r-for-months-heres-what-we-know-so-far-161174

It now seems likely that the vaccine will not stop the spread with the usual two doses. This is only to be expected with something that has an R0 estimated to be about 8. If it reduces spread by about 60% (the figure I see most often in discussions about this, but I do not think anyone really knows for sure), that still leaves an R0 of about 3. That means it will still spread quickly. I think more research is needed here. Plus, more research on what happens if a third jab is given, say 6 months after the second:
https://www.theverge.com/2021/8/5/2...19-vaccine-booster-delta-variants-coronavirus.

I think the bottom line is more research is needed in a lot of areas. And this is required when in places like Australia people are becoming really fatigued with lockdowns etc. The only positive I see is if contact tracing is continued, with an R0 of 3, it may be controlled like the original varient was in NSW. But with Delta at 8 - it failed dismally.

Thanks
Bill
 
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  • #13
bhobba said:
It now seems likely that the vaccine will not stop the spread with the usual two doses. This is only to be expected with something that has an R0 estimated to be about 8. If it reduces spread by about 60% (the figure I see most often in discussions about this, but I do not think anyone really knows for sure), that still leaves an R0 of about 3. That means it will still spread quickly. I think more research is needed here. Plus, more research on what happens if a third jab is given, say 6 months after the second:
https://www.theverge.com/2021/8/5/2...19-vaccine-booster-delta-variants-coronavirus.
I think even without the Delta variant, say with the initial strain, it wasn't good to make long term plans on the basis of vaccination producing herd immunity. The herd immunity threshold is ~(1 - 1/R)/VE , where R is the reproduction number and VE is vaccine effectiveness. For the initial strain, R ~ 2.5, so for VE = 1 (100%) effective, one would need to vaccinate 60% of the population. However, we know from other human coronaviruses that immunity to infection will fall close to zero due to virus mutations in 3 - 7 years, so VE should fall with time. If VE falls to say 50%, then even for the original strain, the herd immunity threshold would rise above 100%. That's why I like the comments by Christian Drosten, where he says herd immunity is irrelevant in the sense that everyone will become immune sooner or later, either by vaccination or natural infection, and if one is refusing vaccination, then one is choosing to be naturally infected with all its risks.
 
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atyy said:
I think even without the Delta variant, say with the initial strain, it wasn't good to make long term plans on the basis of vaccination producing herd immunity. The herd immunity threshold is ~(1 - 1/R)/VE , where R is the reproduction number and VE is vaccine effectiveness. For the initial strain, R ~ 2.5, so for VE = 1 (100%) effective, one would need to vaccinate 60% of the population. However, we know from other human coronaviruses that immunity to infection will fall close to zero due to virus mutations in 3 - 7 years, so VE should fall with time. If VE falls to say 50%, then even for the original strain, the herd immunity threshold would rise above 100%. That's why I like the comments by Christian Drosten, where he says herd immunity is irrelevant in the sense that everyone will become immune sooner or later, either by vaccination or natural infection, and if one is refusing vaccination, then one is choosing to be naturally infected with all its risks.
I never really though about it this way
Everyone, absolutely everyone will eventually become infected….
I was in the mind set that I must avoid future infection at least till my booster is available but then?
I am not sure I will not be wearing a mask and sanitizing at least in some situations after this.

On the twitter link did Christian Drosten leave out a “not?”
I am not being picky I just wanted to make sure I understood it.
“Even if they are (not) high risk they may end up in intensive care.”
 
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pinball1970 said:
I never really though about it this way
Everyone, absolutely everyone will eventually become infected….
I was in the mind set that I must avoid future infection at least till my booster is available but then?
I am not sure I will not be wearing a mask and sanitizing at least in some situations after this.
Well, if we are lucky a booster for the appropriate subgroups will get us up to 99% protection against severe disease that is durable. If it does that, then COVID will become overall as mild as flu. Right now, it's not quite there, numbers for protection against severe disease caused by the Delta variant seem to be coming in around 90% (UK: ~95% Israel: 93%, 91%, 88% from slightly different times and various definitions of severe disease). However, Israel reports that the vaccine breakthrough cases with severe disease usually have multiple co-morbidities: https://www.clinicalmicrobiologyandinfection.com/article/S1198-743X(21)00367-0/fulltext.

pinball1970 said:
On the twitter link did Christian Drosten leave out a “not?”
I am not being picky I just wanted to make sure I understood it.
“Even if they are (not) high risk they may end up in intensive care.”
Yes, that would make more sense - I agree that the translator probably left out a "not"
 
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  • #16
atyy said:
The herd immunity threshold is ~(1 - 1/R)/VE , where R is the reproduction number and VE is vaccine effectiveness.

Just doing a bit of mucking around with the formula. It is estimated the R0 of Delta is about 8 - but with the precautions we are taking, the R is lower. The VE is thought to be about .6 for our current crop of vaccines. Of course, that is an estimate - I do not think anyone really knows. If R is 8, then we need a vaccination rate of 1.46, i.e. impossible as it is greater than 1. So we can't vaccinate our way out of the Pandemic with our current vaccines. We will need a third dose in 6 months. It is unknown what the VE will be then, but it needs to rise to .875 for herd immunity with 100% vaccination. Basically, 70%, 80%, etc., vaccination rates will not do it. For herd immunity at 80% vaccination, you need a vaccine with a nearly perfect VE of 1. Highly unlikely. We must vaccinate at near 100% and have a VE of 90%. It is possible a third dose could give that sort of VE - maybe - but it does seem optimistic. We need better vaccines, third doses and even then still have some restrictions to reduce R from 8, but it will likely vastly reduce the restrictions and be less onerous. In the interim, it is hard to see what else we can do other than have some support (called Job-Keeper here in Aus) for the foreseeable future. Sure, it will run up massive debt and be a terrible burden on future generations - but it seems the only way. Unless, of course, we are happy with the health system swamped with long Covid (it is estimated about 1/3 of cases will get long Covid even if asymptomatic). Mercifully for those vaccinated the chance of dying is low - so we are basically looking at deaths in the unvaccinated. That is what the math tells us. We must heed it.

Thanks
Bill
 
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JNJ - Positive New Data for Johnson & Johnson Single-Shot COVID-19 Vaccine on Delta Variant
https://www.jnj.com/positive-new-da...riant-and-long-lasting-durability-of-response
“Current data for the eight months studied so far show that the single-shot Johnson & Johnson COVID-19 vaccine generates a strong neutralizing antibody response that does not wane; rather, we observe an improvement over time. In addition, we observe a persistent and particularly robust, durable cellular immune response,” said Mathai Mammen, M.D., Ph.D., Global Head, Janssen Research & Development, Johnson & Johnson. “With each new dataset, we build on our solid foundation of evidence that our single-shot COVID-19 vaccine plays a critical role in ending the pandemic, which continues to evolve and pose new challenges to global health.”

Demonstrated strong neutralizing antibody activity against the Delta (B.1.617.2) variant
A preprint submitted by the Company today to bioRxiv contains a new analysis from blood samples obtained from a subset of participants (n=8) in the Phase 3 ENSEMBLE study. These data showed that the Johnson & Johnson single-shot COVID-19 vaccine elicited neutralizing antibody activity against the Delta variant at an even higher level than what was recently observed for the Beta (B.1.351) variant in South Africa where high efficacy against severe/critical disease was demonstrated.
 
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That's good news. Would love to see Delta study data from Moderna and Pfizer too!
 
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kyphysics said:
That's good news. Would love to see Delta study data from Moderna and Pfizer too!

I can't give a full answer to that, but the latest research shows that if you are vaccinated you are half as likely to get delta which changes the calculation I did before:
https://www.forbes.com/sites/robert...to-infect-others-study-finds/?sh=5001e988281c

But to compensate you are less likely to pass it on which means R is lowed. More research is needed on this.

Thanks
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  • #20
kyphysics said:
That's good news. Would love to see Delta study data from Moderna and Pfizer too!
Delta data for Pfizer has been available for quite some time. UK data is AstraZeneca and Pfizer combined. Israel is Pfizer.
UK ~ 49-80% protection against infection, 58 - 88% against symptomatic infection, 95% against severe disease
Israel ~ 39-64% protection against infection, 64% against symptomatic infection, 88-93% against severe disease

References in other posts:
https://www.physicsforums.com/threads/lambda-variant-shows-vaccine-resistance.1005754/post-6525009
https://www.physicsforums.com/threads/lambda-variant-shows-vaccine-resistance.1005754/post-6525216
 
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  • #21
atyy said:
Delta data for Pfizer has been available for quite some time. UK data is AstraZeneca and Pfizer combined. Israel is Pfizer.
UK ~ 49-80% protection against infection, 58 - 88% against symptomatic infection, 95% against severe disease
Israel ~ 39-64% protection against infection, 64% against symptomatic infection, 88-93% against severe disease

References in other posts:
https://www.physicsforums.com/threads/lambda-variant-shows-vaccine-resistance.1005754/post-6525009
https://www.physicsforums.com/threads/lambda-variant-shows-vaccine-resistance.1005754/post-6525216
Thanks for the re:, atty.

So, I was thinking of my post citing Laurie Garrett (former Ph.D. student in Immunology at UC Berkeley and currently a Pulitzer Prize winning science writer) here (see thread for full context):
https://www.physicsforums.com/threads/covid-booster-shots-thoughts-news.1005677/
A multinational study of six months’ use of two-dose Pfizer vaccine also found that efficacy wanes with time, from about 97 percent to a low of 86 percent—still robust. But none of the work involved delta variant exposure. A recent study in Scotland showed that both the AstraZeneca and Pfizer vaccines were considerably less able to prevent delta infection, compared with the alpha strain or original 2020 forms of the coronavirus. (No similar data has been published for the nearly identical Moderna vaccine, but most vaccine experts assume that what holds for Pfizer is also true for Moderna.). . .

My reading of Garrett is that we still don't have long-term data for Pfizer or Moderna on its efficacy in neutralizing Delta.
 
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atyy said:
We get so few chances these days to see real heroes.

We have people who trust the science risking their lives, yet in the west, we have those who do not believe in the science putting others lives at risk:
https://www.news.com.au/world/coronavirus/australia/nsw-covid19-lockdown-byron-bay-locals-blast-antivaxxers/news-story/d984562769f5ab4e4f360486b62f26e3

The contrast could not be starker.

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  • #24
When these studies say “percent effective,” do they mean, “Of a sample size of those with X vaccine, Y amount did not get infected,” or do they mean, “After direct exposure to the delta variant, X did not get infected”?
 
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The mortality rates for COVID are going down over time, independent of vaccinations, it is clear from any data set from any country I've looked at (https://www.worldometers.info/coronavirus/)

Is this not always the case for any new disease? I mean, surely it is an evolutionary thing, as a species we are not only able to adapt to a new pathogen but have adapted to adapt to new diseases once they are among us.

Vaccines help us to tolerate a disease while we adapt and suffer lesser effects from it, but does it take away some of that 'adapting to adapt' evolution?

If we always try to fight a disease with new medications rather than by the evolved processes that help us survive a new disease but also help us adapt to the next 'unseen' pathogen, then surely one day a new disease will appear for which there will BE no medication, and if we are always reliant on a medication to help us through it, then what happens?

(This is just a wider question on how we have evolved to resist future pathogens, I am not seeking to test the wisdom or merits of modern medication, but are the medications themselves 'risk free' if they interfere with evolutionary processes?)
 
  • #26
cmb said:
The mortality rates for COVID are going down over time, independent of vaccinations, it is clear from any data set from any country I've looked at (https://www.worldometers.info/coronavirus/)

Is this not always the case for any new disease? I mean, surely it is an evolutionary thing, as a species we are not only able to adapt to a new pathogen but have adapted to adapt to new diseases once they are among us.
Can you be more specific about what data you are looking at? I mean, provide an example of the drop you are seeing?

It should be true that as the virus circulates and people get infected, recover, and then infected again that their second infection should be less severe. However, I'm not sure if that should be a major factor yet. What is likely a major factor in the stats is that most infections in the first wave weren't recorded, so the CFR/IFR was artificially high.
 
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  • #27
Grasshopper said:
When these studies say “percent effective,” do they mean, “Of a sample size of those with X vaccine, Y amount did not get infected,” or do they mean, “After direct exposure to the delta variant, X did not get infected”?
Say a town has 100,000 unvaccinated residents and 100,000 residents vaccinated with a vaccine that is 95% effective (assume the demographics and behavior of the unvaccinated and vaccinated residents are similar). If 100 unvaccinated residents get infected with COVID-19, you would expect to see only 5 vaccinated residents get infected during the same time period.
 
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  • #28
russ_watters said:
Can you be more specific about what data you are looking at? I mean, provide an example of the drop you are seeing?

It should be true that as the virus circulates and people get infected, recover, and then infected again that their second infection should be less severe. However, I'm not sure if that should be a major factor yet. What is likely a major factor in the stats is that most infections in the first wave weren't recorded, so the CFR/IFR was artificially high.
Yes of course, but can I post screen grabs of the worldometer website and use here? Been jumped on for that sort of thing before.
 
  • #29
@russ_watters , also perhaps I can offer some other things of a more scientific consideration; a paper that seems to have received virtually no attention since when it came out last year in Nature; about 35% of a healthy cohort already had immunity to the effects of SARS CoV2 without any antibodies either being generated or (thus) for which vaccines would have helped.

How did people evolve T cell immune responses to SARS CoV2 before it existed? That'll be evolution at work.

I did wonder, at the time, when everyone was desperate for vaccine roll out (which to be fair is still the case in many of the world's corners, so might still be done now) is assess who already has T cell immune responses because I presume that means a vaccine probably doesn't do much for them?

https://www.nature.com/articles/s41586-020-2598-9.pdf

"The biological role of pre-existing S-cross-reactive CD4+ T cells in 35% of HDs remains unclear. However, assuming that these cells have a protective role in SARS-CoV-2 infection, they may contribute to our understanding of the divergent manifestations of COVID-19, and the notable resilience of children and young adults to symptomatic SARS-CoV-2 infection"

Another paper worth bearing in mind is the role of asymptomatic hosts of SARS CoV2, as there is a large fraction of the population (maybe those found in the Nature paper!) that show no ill effect at all from being a CoV2 host;-

https://www.bmj.com/company/newsroo...vid-19-infection-among-grocery-store-workers/

"One in five (21 out of 104) workers tested positive for SARS-CoV-2, indicating a prevalence of 20% at that point in time. This was significantly higher than the prevalence of the infection in the local community at the time: 0.9-1.3%.

Three out of four of those testing positive (76%) had no symptoms. And of those testing positive, most (91%) had a customer facing role compared with 59% of those testing negative. "
 
  • #30
cmb said:
Yes of course, but can I post screen grabs of the worldometer website and use here? Been jumped on for that sort of thing before.
I guess it depends on what you are talking about. Can you at least point us in the right direction? Or give a handful of bullet points? There's a huge amount of data there.

There is, for example, a global outcomes graph on the "worldwide-graphs" page. It's clearly showing the effect of low early testing, and has had a pretty much hyperbolic drop since the first peak, leveling of at 2.3%. It wouldn't necessarily be easy to isolate an increase in latent/unvaccinated immunity from such data.
The other thing I can post up, of a more scientific consideration, is a paper that seems to have received virtually no attention since when it came out last year in Nature; about 35% of a healthy cohort already had immunity to SARS CoV2 without any antibodies either being generated or (thus) for which vaccines would have helped.

How did people evolve T cell immune responses to SARS CoV2 before it existed? That'll be evolution at work.
That's answered in the abstract: Coronavirus is not new, and it's already endemic. So it is to be completely expected that a lot of people have antibodies:
nature said:
This results indicate that spike-protein cross-reactive T cells are present, which were probably generated during previous encounters with endemic coronaviruses.
It also doesn't say whether that confers any immunity, just that it "may".
 
  • #31
russ_watters said:
I guess it depends on what you are talking about. Can you at least point us in the right direction? Or give a handful of bullet points? There's a huge amount of data there.

There is, for example, a global outcomes graph on the "worldwide-graphs" page. It's clearly showing the effect of low early testing, and has had a pretty much hyperbolic drop since the first peak, leveling of at 2.3%.
Sure, well, I linked to the worldometer website. If you pick a country like the UK and look at the 3.5 waves of infections so far, the ratio hospitalised and dying was already falling before vaccines were introduced.

It's true that the first wave might be considered a source of unreliable data because many people weren't being tested, but I think all the 'positive cases' data is probably unreliable because of that second paper I mention, and other related works, which seem to suggest the number actually infected is substantially greater than ever tested due to the prevalence of asymptomatic carriers.

So for sure, the data is 'nuanced'.

In the UK at the time early 2020, it seemed to me that 'everyone' I came across had a bit of a cold or, more commonly striking, many were complaining of back aches in the region of the lung diaphragm.

I think UK population was significantly infected, at least once, by summer 2020, but for sure you can put that down as a personal anecdote, but it was notable that a lot of folks were complaining of 'irritations'. My point is that I'm already agreeing with any critiques one might have of my own observation above, that the ratio on record (cases v deaths) may not be at all very reliable.
 
  • #32
russ_watters said:
...

It also doesn't say whether that confers any immunity, just that it "may".
I'm just saying there is 'an immune response' sufficient to render the host asymptomatic, i.e. how a vaccinated host ends up (they are not 'free' of the virus either, afaiu).

The issue is for a host's immune response to supress the virus loading to a point where it has no noticeable effect. I don't think the vaccine can, or is being proposed to, eradicate the virus from a host. Is that a claim being made?
 
  • #33
Ygggdrasil said:
Say a town has 100,000 unvaccinated residents and 100,000 residents vaccinated with a vaccine that is 95% effective (assume the demographics and behavior of the unvaccinated and vaccinated residents are similar). If 100 unvaccinated residents get infected with COVID-19, you would expect to see only 5 vaccinated residents get infected during the same time period.
Right, so the first method. In that case, I just recently read a study published in The New England Journal of Medicine with a data chart that seemed to suggest Pfizer is some 85-90% effective against the delta variant. (Table 2)

https://www.nejm.org/doi/10.1056/NEJMoa2108891

Given how effective N95s are, this is very encouraging to me. At least for my own health, anyway. With both shots and an N95, you’re practically invulnerable to it.
 
  • #34
Grasshopper said:
Right, so the first method. In that case, I just recently read a study published in The New England Journal of Medicine with a data chart that seemed to suggest Pfizer is some 85-90% effective against the delta variant. (Table 2)

Let's hope so anyway:
https://www.businessinsider.com.au/...opped-when-delta-became-dominant-study-2021-8

Let's derive Atty's equation posted before. If V is the vaccination rate, and E is its efficiency, then the effective number not vaccinated is 1-E*V. The next generation will have R*(1-E*V) if the reproduction number is R. For it to be in equilibrium, R*(1-E*V) = 1 or V = (1 - 1/R)/E. Less than that, it will die out; greater than that, it will grow.

This was used by a 'so-called' expert to 'prove' we are 'stuffed':
https://abc7chicago.com/coronavirus...id-booster-shot-is-pfizer-effective/10949401/

Now R0 is the reproduction rate under normal conditions, and Delta is about the same as chickenpox at 8. R is the rate that is actually occurring, which depends on several factors such as mask-wearing, social distancing, lockdowns etc. That is how they bring it under control without the vaccine. At least simple precautions such as mask-wearing and social distancing will need to be still used. The R0 is without the vaccine. We do not know how effective the vaccine is at preventing retransmission. If it is at all effective, the vaccine will lower R further. At the moment, there is some evidence it is not effective at all:
https://www.jhsph.edu/covid-19/arti...9-transmission-by-vaccinated-individuals.html

So it looks as though, for the time being, we will be stuck with at least minimal precautions to prevent it from getting out of control, and they may include the occasional lockdown.

At a minimum, I think we will all be getting third doses, and hopefully, second-generation vaccines are effective at preventing vaccinated people from passing it on. That seems the key to herd immunity. And, of course, we need to vaccinate, vaccinate, vaccinate. If we get to nearly 100% and have the third booster, it will hopefully be 8*.15 = 1.2 - a bit below the flu which we can live with. Otherwise - I hate to think. And that assumes it is 85% effective - which I do not think it is - the third dose of a next-generation vaccine likely will be needed:
https://www.abc.net.au/news/2021-07-11/the-australian-next-generation-covid19-vaccines/100271062

I don't think people will like it, but I now think, as is done for Whooping Cough, there will eventually be a no jab, no pay policy introduced.

Getting my second dose AZ at 3.00 pm today. Waited the full 12 weeks.

Thanks
Bill
 
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  • #35
cmb said:
I'm just saying there is 'an immune response' sufficient to render the host asymptomatic, i.e. how a vaccinated host ends up (they are not 'free' of the virus either, afaiu).

The issue is for a host's immune response to supress the virus loading to a point where it has no noticeable effect. I don't think the vaccine can, or is being proposed to, eradicate the virus from a host. Is that a claim being made?

Here's a nice PF thread where we discuss cross-reactive T-cells in more detail with citations to more research on the topic: https://www.physicsforums.com/threa...om-exposure-to-endemic-coronaviruses.1005206/

The two major arms of the adaptive immune response (the humoral response and the cellular response) play different roles in combating pathogens. T-cells help to recognize infected cells in the body to eliminate them as well as help to activate other immune cells (such as the B-cells that produce antibodies). The humoral immune response, on the other hand, produces antibodies that can help neutralize pathogens.

Because antibodies can directly bind to and neutralize viral particles, they help to prevent infection. T-cells, on the other hand, act after infection has occurred since they recognize infected cells. Therefore, T-cells cannot prevent infection; rather, they help to limit the spread of the virus in the body, and along with the antibody response, help to put an end to a viral infection.

Research on the vaccines shows that the vaccines are able to stimulate both a humoral and a cellular immune response. Furthermore, the amount of neutralizing antibodies produced by a vaccinated individual seems to correlate with the degree of protection from infection. Consistent with this idea, clinical trial data and observational data from national vaccination programs does support the idea that the vaccines prevent both symptomatic and asymptomatic infections as well as reduce transmission of the virus. The vaccines do seem to offer a lesser degree of protection against infection for some of the variants such as Delta, which is consistent with laboratory data showing that the Delta variant contains mutations that enable it to escape neutralization from some antibodies. The vaccines, however, still protect very well against severe disease, hospitalization and death even for variants like Delta, which is consistent with data showing that T-cell responses are not affected by the variants (weaker T-cell responses, in general, are also correlated with more severe disease).

In summary, antibody responses help to protect against infection while T-cell responses help to protect against severe disease, hospitalization and death. Prior infection with other common cold-causing coronaviruses might offer some degree of protection against severe disease from cross-reactive T-cells (which could explain why some people have asymptomatic infections while other experience more severe symptoms). This pre-existing immunity, however, does not provide the antibody-based immunity that would be necessary to reduce infection and transmission of the virus. Vaccination is effective at providing this antibody-based immunity (in addition to T-cell immunity).
 
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Likes mattt and bhobba

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