These are very good points. I'd add that herd immunity isn't a clearly defined threshold, either. It's the point at which the effective R in a population is < 1 -- AKA exponential decay. With a circulating virus, depending on how much below 1 you get, exponential decay might take a few months or even a few years to get down to elimination.

The current dip in the UK is trending toward the former. But it's further complicated by the fact that levels of immunity in the population will continue to oscillate up and down. (Nevermind that once schools open in September, 20% of the population with relatively sparse vaccination will be mixing in large cohorts).

Another factor in herd immunity is vaccine efficacy - which is somewhere between 86% and 95% for the mRNA vaccines (and will continue to change). A herd immunity threshold of 90% presupposes a vaccine with 100% efficacy - when your vaccines are not that effective (not to mention, losing effectiveness over time) it bumps the threshold even higher.

Right now, much of the population has some level of "sterilising immunity" from the first round of vaccines and previous infection (i.e. having enough circulating antibodies to potentially block symptomatic infection and transmission). But everything we know about existing respiratory viruses (and indications so far this year) suggest antibodies will wane.

Of course, indications are most people will come away with robust cell-based immunity. (Those plucky T-cells and B-cells). But eradication for the UK looks *very* close to impossible given the near-total-abandonment of public health measures recently.

> But everything we know about existing respiratory viruses (and indications so far this year) suggest antibodies will wane.

Not necessarily the case. Infections with HCoV-229E produces durable immunity and reinfection is due to antigenic drift:

https://www.biorxiv.org/content/10.1101/2020.12.17.423313v1

That it at odds with prior studies that found ~12 month reinfections with coronaviruses, but it is with considerably better methodology.

And it is simultaneously: not clear that vaccines produce sterilizing immunity, not clear it is necessary to do that at all, and not clear if how much measurements of NAbs correlates with sterilizing immunity.

I can tell you a story about how delta reaches 90-100% thresholds of herd immunity in this wave and burns itself out and we don't see it much again for 3-5 years in countries like the US/UK. Or I can tell you a story about how it keeps coming back every year with 2 or 3 waves. Anyone who tells you they know which of those outcomes must be correct probably knows a lot less about virology than they think they do (even if they have a degree). I'm reasonably hopeful its the former, but I never predicted delta and thought we'd be virus-free this summer and was wrong.

Even in the worst case though the vaccinated/recovered are never going back to 2019 levels of susceptibility to severe outcomes, so we're looking at a steady drip-drip-drip of people killing themselves to avoid vaccination up until we get bored with that and they pretty much disappear (that's where T-cells and B-cells and cross reactive partial immunity to all future variants comes in).

Setting up two likely scenarios is a very reasonable way of approaching future development, both scenarios sound likely to me.

We could look at the flu for clues, in that case every year will have one or more variants that are the most prominent.

I'd argue that in the age category with the most infected (10-29 years old) in the UK, that these people are not killing themselves due to their young age.

And the elderly have already gotten the vaccine and are thus up to eight times more likely to not get infected.

Flu is a bad example --- it has 8 "segments" (basically "chromosomes") that get reassorted among the offspring when a cell is infected by multiple strains, leading to a crude form of "sexual recombination". (The numbers after the "H" and "N" indicate the variant-numbers of the Hemagglutinin and Neuraminidase "segments" that the flu-variant got; a cell infected by H1N1 and H2N5 will also produce some H2N1 and H1N5 offspring in addition to H1N1 and H2N5, leading to very rapid genepool evolution)

By contrast SARS-CoV-2 only has a single chromosome, and so it primarily evolves via "genetic drift". While it's _possible_ for a cell infected by multiple SARS-CoV-2 variants to generate "chimeric" offspring via a process called "crossover" AKA "homologous recombination", that mechanism is much less effective than the simple segment-reassortment that drives flu evolution.

> We could look at the flu for clues

Like the 1918 H1N1 second wave mutation that caused ARDS in 20 year olds?

We still have no idea how that happened, but with this coronavirus evolving to be more transmissible/virulent that is still on the table. If it can evolve to become more transmissible but at the cost of triggering ARDS like that, then it will face evolutionary pressure to do so.

And hospitalization rates of 20-29 year olds aren't anywhere near as good as the fatality rates. While the death rate drops by a factor of 2 every 8 years, the hospitalization rate drops by a factor of 2 every ~15 years. And delta has 2x the hospitalization rate of alpha across age/sex/deprevation/comorbidity matched controls. It should still be about a 1-in-50 chance of hospitalization for 20-29 year olds. There's no proof that number can't continue to get worse.

> eradication for the UK looks very close to impossible given the near-total-abandonment of public health measures recently.

I don't support the recent abandonment of restrictions, but could that policy, followed up by stricter restrictions in a few months time actually be helpful for eradication? Eradication is likely a hopeless prospect in the UK anyway, because there is no political will for closing the borders. But it's interesting to conjecture.

The ship has sailed on eradication. We're ALL going to get Delta at some point now, it's just a question under what circumstances (and whether the antivaxxers will have sufficient numbers to denial of service the healthcare system as they die).

> We're ALL going to get Delta at some point now,

That's by no means certain; even ignoring the possibility of effective countermeasures, a more transmissible variant could displace it (if we’re lucky, it could also be one producing less severe disease, the way it was when Epsilon variant for a while displaced most others in California, before Delta, which is more transmissible than Epsilon, took hold.)

Tangential question: what is the mechanism by which we observe ‘displacement’ of earlier strains? Is it just the exponentially higher transmission factor of the variant that is making it relatively disappear? Or are they somehow also get out-competed directly?

The former: once you have COVID you're immune to it. Unless a strain totally evades the antibody response of recovered individuals (very unlikely), then they're no longer capable of spreading it.

So if there's overall less replicants of one strain then the other, then the population will effectively select for the more infectious one. Actual geography of course is also key here though: if a carrier flies over to an unexposed area with any strain, it's going to take over if the other one doesn't make it there.

Add to that, the more it multiplies and spreads, the more chance of mutations leading to more variants. Needing updated vaccines, booster shots of existing, and/or higher rates needed to reach herd immunity.

Didn't the UK have another lockdown for this wave too?

Herd-masking seemed like a no-brainer from the beginning. It will be really hard to go back to that in the US after the CDC giving the all clear to go maskless.

You can't expect people to wear masks forever.

True, but maybe just until the pandemic is actually under control. Which would happen faster if people kept their masks on.

>at least unless we get a vaccine-resistant strain.

...which will happen promptly. The selection pressures are perfect. You already have a variant with vaccine breakthrough, circulating in a partially vaccinated population.

I don’t know if you can make that bet - evolution of the virus needs to conserve the current mode of cellular entry and attachment and fitness of spike appears to be the main driver at present - and then spike mutation has driven drift from the original vaccine target leading to a degree of immunity ‘escape’.

So the question is, is the virus now in a local minima where it is highly adapted for spread (ie big increase in R0 from ‘original’ virus) and are those selective pressures in a situation where the virus can’t jump into a full immunity escape mode without climbing down off mount improbable and taking another face?

My bet would be that the selective pressures may continue to drive fitness for reproduction, but won’t lead to immunity escape because spike is too conserved

I'll echo that this is a reasonable assessment. In evolutionary hill climbing, the fitter a protein the fewer paths there are to climb higher [0]. Art Poon has some interesting work that effectively maps viral phenotype space by looking at compensatory mutations [1]. He induces deleterious mutations in page phage, grows them until they recover fitness and then assesses if they regained fitness by reversion or compensation. The worse a deleterious mutation, the more likely a compensatory mutation is to arise.

The more optimized the covid spike becomes, the harder it is to get better. What frightens me are polymerase mutations.

[0] Darwinian Evolution Can Follow Only Very Few Mutational Paths to Fitter Proteins https://science.sciencemag.org/content/312/5770/111

[1] The rate of compensatory mutation in the DNA bacteriophage phiX174https://pubmed.ncbi.nlm.nih.gov/15911582/

> What frightens me are polymerase mutations.

What are these in layman's terms?

Mutations in the genetic replication machinery of the virus. All the world's worst and most untreatable diseases tend to have very fast, but very low quality polymerases.

This means they replicate quickly, and generate mutagenic variants quickly. HIV and Ebola have this in common.

Delta is already selecting for viral load over vaccine escape - if it keeps getting faster then it could become more dangerous, but it would also increase the rate it can explore it's genetic "phase space".

Rather than increasing efficiency, I'd be concerned about loss of function in the error checker. This would spike the mutational rate (and the mutational load).

Interesting, thank you. If I understand correctly, viral load mutations are the current and quickest path to spreading faster, currently. It hasn't selected as fast for vaccine escape, yet, which is not to say it isn't trending in that direction with delta?

Or, we're kinda f'd with regular transmissions at the moment, and vaccine escape is a possible accelerant?

The problem is closer to whether the spike protein is near an local maxima for infectivity since it's involved in binding to ACE receptors. Since mutations in COVID seem to conserve the spike protein region, it presently looks quite likely that it can't be changed very much without performing worse. Hence the viral replication optimum: spreading to more individuals makes the virus dominate the population quicker.

Evolution does whatever leads to more of the successful thing existing, so viral loading was a pretty obvious move: the question is whether there's any vaccine-evasion which doesn't compromise that advantageous (Delta suggests yes, but its possible that's as far as it can actually go).

I don't know or haven't seen any evidence that polymerase mutations are responsible for the increased R0 of Delta, although it's certainly possible.

What we do know is that the Spike protein is essential for COVID cellular binding.

We also know that spike has mutated between 'vanilla' COVID of 18 months ago and what all vaccines target, and Delta. This makes sense, because the spike (or S) protein wasn't optimised for binding to Human ACE2 receptors; over time mutations in S (ie with Delta) have lead to increases in binding affinity with ACE2, the result being that Delta is more likely to infect a cell with the same viral load as 'Vanilla'. This would be a perfectly acceptable reason for the uptick in viral loads in Delta and infectivity and hence R0.

We are lucky/the vaccine researchers are smart in that S is quite antigenic (that is, triggers a good immune response, although in a 'natural' infection people will produce antibodies to many parts of the COVID virus), and because the selection pressures driving improvements in ACE2 binding affinity of S have not lead to such a great conformational change that antibody responses are useless (ie antibody-antigen affinity is decreased in Delta, but still effective), our vaccines against the earlier S protein are still effective.

Because of the way evolution generally works, pressures driving S evolution tend to end in a local minima (or maxima, depending on your way of looking at it - i tend to think in terms of conformational entropy so hence Xornot and my use of different terms for the same concept) - or as I mentioned earlier, 'Climbing mount improbable', a term coined by Dawkins in the book of the same name.

It is because it is very hard to get out of these local minima that the human body is full of such oddities, such as an eye that is designed with the nerves in front of the photoreceptors, resulting in a blind spot - it's easier to adapt around the minima to reach a new optimum then it is to reinvent the eye with the nerve in the position that would be logical from a functionality standpoint)

Therefore, it is very very unlikely that the S protein, or the virus, will be able to mutate to a S protein that is so radically different that it escapes antibody-antigen affinity from the vaccines we have today - the S protein would basically have to be completely redesigned, which is really unlikely to occur by the gradual process of evolution. Ie the chances of shaking the RNA coding for S into a new functional protein that works and is a completely new, novel shape, is infinitesimal.

So - basically, total vaccine escape is really really unlikely. Like, number of grains of sand on earth unlikely, if not more so. But polymerase mutations could increase the rate at which the grains of sand are sifted.

It is not something that I personally would lose much sleep over - we don't have any evidence from nature that I am aware of (ie flu virus etc) of highly conserved/selected proteins all of a sudden spitting out a completely new model - basically new diseases that we worry about come from species shifting (ie... let's just say SARS to avoid a debate about COVID origins)

I agree with everything you wrote, however - when we bet, we need to consider the stakes and the payoff.

So the important question is: should "we" take the bet on that immunity escape? Or should we not take that chance?

My opinion is that we should act decisively to avoid the bet.... but the UK government clearly feels lucky.

Measles, polio, and smallpox beg to differ. The varicella vaccine is fairly new, but I haven’t heard of a vaccine-resistant strain evolving. Pertussis seems to be an odd duck, and its vaccine is not as effective as people would like.

History is mixed here, but most of the mandatory vaccines seem to be extremely effective and to work well for at least decades.

Those also have low breakthrough rates (assisted by high vaccination percentages), giving it relatively no opportunity to evolve. They also had millennia to reach (and then work to maintain) peak fitness, while COVID is still encountering beneficial mutations somewhat frequently.

Presumably also the human species had time to co-evolve some resistance to these illnesses. I shudder to think at the cost... hundreds of millions of lives for smallpox alone...

I'm not sure if it's inevitable given how crucial the spike protein is and how strongly it is being conserved. Even with the Delta variant, which is much more infectious and contagious, the vaccines are only modestly less effective and still highly effective at preventing severe illness and death.

“ Instead of 60% vaccination, you'd need 90%, and will likely overshoot that.”

60% (Vaccinated + Previously Infected)

Delta variant can reinfect.

It's not a binary consideration, but you have expressed it as such.

I also kept in mind that amount of R0 for the "Indian variant", until last week I saw it halved to 4..5×.

Then you realize that a transmission rate among the timid in ShyFleetersLand and the compulsive in LetsHugLand cannot be the same. Then you realize that that very average number needs explanations of the underlying model to be meaningful - it comes from societal behaviour not just from intrinsic viral properties.

> Probably Delta will blow through literally all the remaining unvaccinated people and that'll be the last surge, at least unless we get a vaccine-resistant strain.

I think you're right, but that will still happen over years in multiple waves. Barring some sudden uptick in people changing their mind about vaccination.

> It wouldn't surprise me if the UK's cases are now dropping because they reached that threshold, but I doubt the US is there now.

Given the enormous US Covid outbreak, the US is likely not far away. We're at 70% adult vaccination and had a minimum of 100 million prior Covid infections. Also throw in tens of millions of people that likely have natural immunity to Covid.

The biggest question with Delta is going to be the matter of repeat infections and how long the vaccines, the vaccines + prior infections, and prior infections (without vaccination) all hold up against it. To say nothing of what variations will follow next after Delta. Is there actually herd immunity to be found with Delta, or will people just keep getting variations of Covid from here forward. I don't believe there will be herd immunity for any nations, there will just be far lower mortality rates due to prior virus exposure and the vaccines. Some non-trivial % of the vaccinated population will continue to get Covid. If there was a chance to squash Covid with the early strain via herd immunity, those days are very long gone.

The great lie still being persisted for the benefit of the agitated public, is that Covid is going to go away courtesy of vaccinations. The authorities have pitched that to the public from the early days of the vaccines to try to max out the vaccination rates. Do this and Covid goes away. The vaccines are never going to stop Covid, they're going to continue to dramatically reduce the mortality rates (which is critical, however the public still doesn't widely grasp the reality of the forever Covid future yet).

If the forever-COVID reality for 95+% of the population is "you really, really ought to get that annual booster shot" (instead of "get the flu shot iff it's convenient"), that's not actually so terrible.

If it becomes century-long endemic in the population, kids are exposed to it, likely creating a productive exposure-related immune reaction until they're old enough to get an mRNA vaccine.

Definitely. I don't think it's terrible at all given the alternative is tens or hundreds of thousands of additional people dying from Covid per year in the US. I guess we'll soon see the extent to which the public can be convinced to get booster shots every year. The governments of the world will have their jobs cut out for them, there will be a lot of resistance to forever Covid vaccinations as time goes on (and very lucrative for big pharma; Pfizer, BioNTech and Moderna are going to make a stupid amount of money over the next few years).

What will be interesting to find out in the near future, is if high vaccination rates + prior infections reduce Covid deaths below, say, 50k people in the US every year, or whether we're forever stuck with a sizable population killer no matter what (short of implementing elaborate forever cultural systems of lockdown; as in, those counter measures will have to become ingrained deeply into the culture, accepted and automatic). The next decade is going to be very weird and interesting on that front.

Vaccination is great but in addition to that we could also cut the ongoing death toll through public health campaigns to eliminate hypovitaminosis D. This could be done relatively cheaply.

https://vitamin-d-covid.shotwell.ca/

From a public health perspective, the total number of deaths in a pandemic is less important than the timing of the case load. Too many cases in too short a period of time causes havoc in the health care system, and then helps lead to deaths from conditions unrelated to the pandemic (because hospital care is unavailable).

It may sound callous, but in terms of first priorities, reducing the total number of deaths from COVID19 has never been our #1 priority (to the extent that we've had any clearly formulated priorities at all). The implicit goal, as we were all saying in the spring of 2020, was/is "flatten the curve".

The actions of my local government align with that. Keep the hospitals from being overwhelmed, but if you die because you didn’t get vaccinated, too bad so sad. Which seems the right way to handle it. Allow folks their individual freedom as much as possible, but don’t break the health care system.

> Allow folks their individual freedom as much as possible, but don’t break the health care system.

Unfortunately, these two goals, when combined with an infectious agent with a good-sized R0, are really in opposition to each other.

I don't think they need to be. At least not within reasonable bounds.

There's certainly an interesting discussion to be had surrounding individual freedoms vs the common good in a pandemic, but I'm not sure as to what extent we can even have those discussions while an embarrassing number of people feel that just being asked to wear a covering over their face in public spaces is an intolerable violation of their personal freedoms. When even the smallest requirements intended to protect the public's health are treated as if they were the harshest forms of oppression imaginable there simply isn't any room left for debate.

Still, for the population that believes a degree of concession can be reasonable and appropriate under such extreme conditions as a global pandemic I think it is possible to strike a good balance between individual freedom and individual and collective responsibility. I think we can work to protect freedoms while also insisting on some measures to help reduce the spread of a virus.

It doesn't have to be an either-or situation at least.

It's probably going to end end up the same as the Spanish Flu influenza variant, occasional localized outbreaks which are much less severe than the original pandemic.

U.S. is only at 50% fully-vaccinated, with several states in the high 30s to 40s. I could believe 70% with at least one shot but haven't seen any statistics to that effect; it doesn't matter much since Delta is still pretty dangerous to partially-vaccinated people. We had 35M recorded COVID cases; I'd believe about a 2:1 undercount, so about 70M total cases (~22%). Vaccines + previous cases was likely past herd immunity for the original variant (hence why cases dropped dramatically after vaccines came out), but with Delta's increased herd immunity threshold we should expect another 50-70M cases within the next few weeks.

> I could believe 70% with at least one shot but haven't seen any statistics to that effect

Good guess. As of today, that's the exact number:

https://www.usnews.com/news/health-news/articles/2021-08-02/...

Just for clarity, that's "70% of American adults".

18% of Americans are 15 or younger [1], below the youngest approved vaccine age (the Pfizer vaccine is approved for teenagers as young as 16), so that's (0.18 + (1-0.18) * (1-0.7) = ) ~42% of Americans who haven't even received 1 shot, and 58% who have.

(There may be some error in that, if far more or far less than 70% of non-adult vaccine-eligible people (teenagers aged 16 or 17) have gotten at least one shot, but it probably doesn't change the overall percentage that much.)

[1] https://www.cia.gov/the-world-factbook/field/age-structure

Need to redo some numbers, Pfizer has been approved for ages 12 & up for a couple of months now [1]. Our World In Data lists that ~50% of American population is already fully vaccinated.

[1] https://www.fda.gov/news-events/press-announcements/coronavi...

I found:

https://www.mayoclinic.org/coronavirus-covid-19/vaccine-trac...

...to be quite interesting for covid-19 vaccination information. For example, the state with the lowest rate of at-least-one-dose vaccinations for people 65 and up is West Virginia, at 83.1%. Most states are 90+% or better for that age group.

It's 70% adult vaccination at one shot or more (I specified adult in my comment). That's all over US news today. The US is at 165m fully vaccinated (or 50%), most of which are of course in the adult segment.

A very large number of those adults also aren't going to need two doses to reach high levels of protection (against severe outcomes), due to prior infections. One mRNA vaccine dose + prior infection will get you there.

Combined with the recent surge in vaccinations due to Delta concerns, the US will probably see the same drop-off that Britain has by late August - early September.

> The great lie still [...] is that Covid is going to go away courtesy of vaccinations. The authorities have pitched that to the public from the early days of the vaccines

That is (1) outrageously hyperbolized and (2) completely wrong. Delta wasn't known to have this level of transmissibility until the last three weeks. People, experts, doctors, "authorities", whatever, you want to label them 100% believed sincerely that we were on a path to the elimination of the outbreak.

Cut the bullshit, basically. Yeah, yeah, I know it's HN and everyone wants to think they're smarter than everyone else. But you aren't. You're retconning brand new science to make prior understanding into a "big lie". That's really awful.

> Delta wasn't known to have this level of transmissibility until the last three weeks.

Delta was formerly known as the India(n) variant. We've known it had high transmissibility since April or May.

The relevant experts - virologists, epidemiologists, etc. - neither believed nor claimed that we were on a path to the elimination of the outbreak. They've consistently stated that the virus will be around for at least years, probably decades, possibly forever.

To be clear, I meant "elimination of the outbreak" in the sense of an endemic virus that produces a steady case rate. Clearly no, no one expected this disease to be eradicated.

Well, you and I didn't. I know quite a few people who've been talking since June about how they're comfortable doing suchandsuch "as soon as Covid is gone", and I'm not sure what they could mean by that other than eradication. It would seem to me that by an endemic standard, the Covid outbreak was gone from the US between May and July and has only just recently made a resurgence.

That seems nitpicky. There are lots of non-eradicated endemic diseases (ebola, malaria...) that are objectively much scarier than covid. But we don't freak out about them because they are well-controlled and rare. A covid mitigation regime that keeps its R0 under 1 and its outbreaks local and non-spreading would be very much the goal here.

> It would seem to me that by an endemic standard, the Covid outbreak was gone from the US between May and July and has only just recently made a resurgence.

Pffft. Yeah, not even close. At its lowest, the covid death rate was 5x higher than average deaths from influenza over the past decade.

At what specific death rate would you be comfortable saying "okay cool" and treating Covid the same way as other diseases?

I don't mean for this to be a trick question. 5x the flu is within my comfort zone, but 2x or 1x or even 0.5x could all be reasonable answers. The answer that's not reasonable, but is by far the most common answer I've gotten, is that no Covid deaths are acceptable and we should never stop taking extreme measures to suppress them.

Gah. Influenza kills more people in the US than any other infectious disease, and frankly it isn't even close. You aren't making any sense here. I cited that number, clearly, as an UPPER bound beyond which we couldn't possibly view an outbreak as acceptable.

I don't view a statement that puts 100k deaths/year as within your "comfort zone" as a serious attempt to engage, sorry.

I dunno. I'm not gonna browbeat you with more arguments for my risk tolerance if you're not interested in them, but I think you're avoiding looking reality in the face here; there's a lot of people an order of magnitude more risk tolerant than me who wanted to open crowded bars in February or earlier. A policy that expects restrictions will remain in place as Covid deaths fall, but can't offer any explanation for why they should remain in place or when they'll no longer be needed, seems doomed to the same kind of mass defection we saw in mid-2020.

People aren't necessarily risk tolerant they largely are utterly incapable of grasping relative magnitude of risk and largely believe that gains in freedom will accrue to them and costs will accrue to other people.

Yeah, but a politician can’t say that…so the experts close to the politicians tend to follow the political narrative instead. The ugly result is a lack of trust in the experts, the science, and the politicians when there are setbacks to that political narrative.

Yeah. This has been my impression, too. I’m not aware of anyone who thought vaccines were a path to total elimination. But then, my only news source is HN and some science YouTube channels.

The vaccines are/were a path out of a pandemic.

That's something to strive for, but extremely different from "elimination"

IMO users who push flat-out lies like that should be banned. HN should not be a source of disinformation.

Where are you getting 100M confirmed infections?

I can't speak to what the parent comment might have been referencing, but the CDC estimates 120MM infections through May 2021.

https://www.cdc.gov/coronavirus/2019-ncov/cases-updates/burd...

Thank you

Where did you "hear" it has an R0 of 8-10? It's not time to be imprecise.

If you're referencing the CDC's case study from Provincetown, I think it's important to point out that the R value cited is the R value during Bear Week, not on average.

When people present R0 as a property of the pathogen, you can take it as hot panicky air.

From wiki: "R0 is not a biological constant for a pathogen as it is also affected by other factors such as environmental conditions and the behaviour of the infected population."

Wiki also lists this number as the current R0 (though without a source, as far as I can see). Found this study too in attempting to answer your question: https://www.fil.ion.ucl.ac.uk/spm/covid-19/forecasting/

And learned the difference with Rt today (which some others are quoting, eg for Alberta), is that Rt is computed, while R0 is a guess based on a model, to try to normalize Rt so that it is more comparable over time and place. So I thought that was cool!

> It's not time to be imprecise

:) Many of us have felt something along those lines since the early times.

But e.g. the viral load for said variant was reported as _1000x_ Wuhan weeks ago, value changed to _3x_ days ago.

I read the emergence of Tinnitus after COVID-19 weeks ago at _67%_, today at _0.shmbrmbsomething_.

We are flooded in bad numbers. (And of course, that R0 is also circumstantial, vs the examples above...)

Look, just fresh in came an article from Shabir A. Madhi, Dean Faculty of Health Sciences and Professor of Vaccinology at University of the Witwatersrand; and Director of the SAMRC Vaccines and Infectious Diseases Analytics Research Unit, University of the Witwatersrand

COVID-19 herd immunity? It's not going to happen, so what next?

https://theconversation.com/covid-19-herd-immunity-its-not-g...

> we would need to get close to 84% of the global population developing protection against infection (in the absence of non-pharmacological interventions) in as brief a period of time as possible

(...also, there, you find «the reproductive rate [...] is probably closer to six rather than three»)

The UK Office for National Statistics actually puts out estimates for the prevalence of covid antibodies (from both vaccines and infections combined), and you are right on the money!

They estimated that as of June 14, 89.8% of the population would test positive for antibodies.

https://www.ons.gov.uk/peoplepopulationandcommunity/healthan...

Indeed, even with Delta’s terrifying R-value, this seems like enough to suppress the virus.

Delta's R numbers are not uniform, but certainly are not 0.

Some easy-to-grab stats from Canada's worst covid province which is dealing with a Delta wave:

    Alberta provincewide: 1.48 (1.38-1.59)
    Edmonton Zone: 1.37 (1.15-1.61)
    Calgary Zone: 1.50 (1.37-1.64)
    Rest of Alberta: 1.48 (1.26-1.73)

https://www.alberta.ca/covid-19-alberta-data.aspx (Fyi, Alberta is Canada's version of West Virginia. It is the national heart of COVID resistance/denial.)

I don’t know any specifics about this, so this as an attempt at asking questions of what to possibly expect from those numbers. Alberta seems to be 63% vaccinated, which seems to put them well above average for the US? And it looks like those numbers are currently computed for the day before the latest surge in cases took off?

Edit: later learned the parent is talking about R0 and you are talking about Rt, so those numbers are not directly comparable anyways.

Oh. Whenever i see "R number" i think Rt. Thats what the news and government spokespeople use.