You can walk yourself through the reasons why with simple math, really.

Every disease has an estimated R0. The number of people an infected person will infect. You probably have heard of this.

Delta, last I checked, has an estimated R0 of between 5 and 9.5.

Vaccination levels reduce that. And it's a simple equation. All you need to know is the vaccination rate for your population, and an estimated efficacy rate of the vaccine.

And from that, you can figure the new adjusted Rt:

rt = r0 * (1 - (vacRate * eff))

And that's it. And no matter what efficacy rate you pick (infection efficacy estimates for mRNA against Delta vary widely), the resultant rt will be less than the initial r0.

And if it's less, then that effectively means that the disease is less contagious for that population, compared to how contagious it was pre-vaccination.

And less contagious is better than more contagious.

So now I am legitimately curious. What part of the above reasoning do you actually disagree with?

(Incidentally, vaccination also improves your chances of avoiding future infection, even if you've already been infected.)

What is the efficiency against transmission of the latest mutations? AFAIK there is a great efficiency against bad symptoms, but much lower efficiency against transmitting the disease to others, but I don't know the latest numbers.

(Copied from elsewhere in the thread:)

Last I heard, the CDC gave a 95% CI of the mRNA vaccines being 26% - 84% against infection (from Delta), and there's an additional 40% - 60% protection against infecting others (I've seen that estimate in multiple places but I don't know the source). If that's true, it suggests an overall range of 55.6 - 93.6 effectiveness against infecting others.

Over the summer Florida has been in the news because of an ongoing epidemic spike. Using hospitalization rates, the spike started sometime in early July. By late Sept it is almost gone. The fully vaccinated rate increased from 48% to 59% during the same time period. Is the receding fully explainable by the increase in vaccination rate, or can we consider other forces at play, for example forces of outside human control that have been at play in every single epidemic before the vaccines era?

https://coronavirus.jhu.edu/region/us/florida

https://data.democratandchronicle.com/covid-19-vaccine-track...

Edit: I plotted Rt as a function of eff, assuming r0=7 and vacRate=1. Rt goes below 1 only for values of eff > 0.85, which means that given the numbers for eff you gave in a different post "overall range of 55.6 - 93.6 effectiveness against infecting others", there are plenty of scenarios where vaccines by themselves cannot stop an infection wave even if the population is 100% vaccinated.

https://www.wolframalpha.com/input/?i=plot+y+%3D+7+*+%281+-+...

https://www.wolframalpha.com/input/?i=solve+1+%3D+7+*+%281+-...

Edit2. For a 0.59 vacRate, there are some solutions for R0 * (1 - 0.59 * eff) < 1 with eff in [0, 1] and R0 in [0, 9], specifically there are solutions for R0 < 2.x Not going to cut it for 0.59 vaxx rate and delta, no matter how effective the vaccines are.

https://www.wolframalpha.com/input/?i=plot+1+%3E+y+*+%281+-+...

Some combination of death, natural immunity, vaccination, distancing, mask use, etc. What other forces are you suggesting?

Note that the more populous counties probably increased vaccination at a greater rate, like Miami-Dade went from 56% to 72% over the same time range.

Natural immunity as a direct effect of an infection wave is my first guess. In some circles 'natural immunity' has become a dirty word :/

The assumptions between the equation rt = r0 * (1 - (vacRate * eff)) are too simplistic and unable to explain Florida infection wave behavior. There are more variables that we ignore when focusing only on Rt and vaccines.

The silver lining: At some point the whole population would have been exposed to covid, either through vaccines, infection or both. At that point the whole vaccination rate / effectiveness discussion becomes moot. Perhaps I wish the public discourse would keep an eye on 'estimated population fraction exposed to covid' that includes all plausible factors.

Yes, I brought up that equation merely to illustrate how vaccination alone can impact Rt downward - for a while it was unclear to me exactly how "partial vaccination" (before herd immunity) was a benefit; that helped me see that it really just mean it slows down the doubling rate until you get to Rt=1. But overall, Rt is impacted by all forms of mitigation including natural immunity.

The way I actually use that equation in my personal dashboards is to estimate what Rt "would" be, at today's mitigation levels, if no one had gotten vaccinated. So for instance, Portland's Rt is currently 0.92 (according to one model). By plugging in Portland's vaccination rate and efficacy estimates, you can estimate that Portland's Rt would be around 2 today if not for the vaccinations, if all other mitigation were the same.

On the one hand, 2 is a lot better than those estimates of 5 to 9.5, which means that we're impacted a lot by current mitigation practices (masks, distancing) and natural immunity. On the other hand, 2 is huge! Given estimates on infectious periods, that means that currently our cases halve every 90 days or so, but 2 would mean cases would be doubling every week or so. Gargantuan difference. So just an illustration that vaccination has a big impact and matters a lot.

or maybe they're just reporting data creatively

https://www.reddit.com/r/dataisbeautiful/comments/pxizb1/oc_...

and it seems like it works

Alabama, Georgia, Missisipi, South Carolina all show a similar profile:

https://coronavirus.jhu.edu/region/us/alabama

https://coronavirus.jhu.edu/region/us/georgia

https://coronavirus.jhu.edu/region/us/mississippi

https://coronavirus.jhu.edu/region/us/south-carolina

Edit: Also Oregon and Washington, lest we suspect there is a grand RedState conspiracy at foot.

https://coronavirus.jhu.edu/region/us/oregon

https://coronavirus.jhu.edu/region/us/washington

This is missing the last step of calculations as any degree of lower r0 doesn’t necessarily prevent endemic disease. My understanding is that at this point, vaccines are about keeping symptoms mild and ICUs at low capacity through reduced spread and more effective immune responses. This seems compatible with the view that we will have to live with this disease for a long time.

you argumentation is correct but misses a point. the vaccs may encourage new variants due to evolutionary pressure.

That point is incorrect; discussed elsewhere.

I mostly agree with you but "And less contagious is better than more contagious." is a giant hand wave in a logical argument. You should explain what specific outcome in the longer term improved by this and justify that.

The implicit assumption in that statement is that "less contagious" means "less disease" means "less casualty".

Other ideas https://boriquagato.substack.com/p/the-vaccinated-supersprea...

It is all much more opaque than the "get your vacc and your old live comes back" evangelists want you too believe. Corona will stay.

I don't know what pro-vax people are saying "get vaccinated and your old life comes back", that seems a mischaracterization to me. The reason to get vaccinated is to protect yourself and others from the disease.

Once everyone (young kid less than 5 years old) can get the vaccine if they want to, I really doubt Covid restriction will stay in place.

Take the vaccine (Moderna if you can pick), significantly reduce the health risk of covid on you. Also, helps to dampen the overall rate in the county and reduces the risk new mutations that may create more breakthroughs.

If you're complaining about the withdraw of mitigations, that's because people and states have refused to participate in the mitigations as a whole.

If they were compliant, we'd be in a situation like Australia or Taiwan. Masks optional, nearly normal (they have restrictive borders), open concerts, and lockdowns only when a couple of cases pop up.

Australia has been on significant lockdown for long stretches at a time, I am not sure I'd consider that "nearly normal" since they have to keep locking down every time Covid is reintroduced somehow.

They are keeping Covid rather low, though I would not trivialize the cost of doing so.

"and reduces the risk new mutations" likely the opposite is true. It is called evolutionary pressure.

I will get vaccinated next year since I move back to China then. They insist and I am okay with it since I get something in return.

> "and reduces the risk new mutations" likely the opposite is true. It is called evolutionary pressure.

Chicken and egg problem: You can't have evolutionary pressure without an environment to operate in. Vaccines reduce the space in which they can attempt to successfully mutate.

That environment of evolutionary pressure is exactly what is being created. An environment where strains with higher fitness for immune escape are more able to spread, in a compounding manner. Particularly with leaky vaccines as we're using for c19 that do not prevent contraction with high efficacy.

Please read this - even just the 'Prevention' section for a real world example. https://en.wikipedia.org/wiki/Marek%27s_disease#Prevention

or read how antibiotic resistance comes about, which seems to be less contentious / politicly affected... But the same evolutionary mechanism is at work.

That's not how evolutionary pressure works. If fewer people are infected, the virus has fewer opportunities to mutate. Among those people, any surviving mutation has (by definition) a greater ability to escape the vaccine, but that's not the same thing as saying that the vaccine increases the chance of a new mutation.

There's a missing part to this by the way: you need a reservoir for new mutations to replicate in, and they have to be mutations which become dominant in the reservoir.

Since the vaccines reduced R(eff), generally below 1 (so far observed), any chain of infection through vaccinated people tends to terminate - not continue. Which means however vaccine evading that virus is, all of it dies.

This all changes if you have a large group of unvaccinated people presenting no challenge to it. Freely spreading for a whole lot of cycles through that population means more vaccine-resistant copies are now out there, with more opportunity to challenge vaccine resistant individuals they come into contact with (since R(eff) in the unvaccinated is ~8).

This is incorrect. I encourage everyone to get vaccinated if they can, but there is no reliable evidence that this reduces R(eff) below 1.

https://www.businessinsider.com/delta-variant-made-herd-immu...

R(eff) lowers the higher the vaccination rate. There are some pretty obvious % targets depending on your R(eff) initial. For the initial population number it's ~90%.[1]

So no, I am in no way wrong.

[1] https://grattan.edu.au/news/race-to-80-how-we-mapped-austral...

"no reliable evidence" - of course vaccination helps bring R(eff) lower. That's just the way the math works. If R(eff) is already low enough due to other mitigation, then additional vaccination helps bring it below 1. We see that all over the nation now, R(eff) rates dipping below 1 as vaccination rates increase.

I have trouble visualizing that, but if that's true it's just more reason to do whatever we can to get local Rt < 1. Vaccines get us partway there, other mitigation efforts like mask use, distancing (and natural immunity) get us partway there as well.

I'm personally vaccinated and not very worried about getting the disease if I have to be out and about. I feel my personal risk is low. But in terms of societal/community risk to others, that's why I have a personal policy of limiting myself socially so I don't contribute to spread.

The local metrics I personally follow are:

1) Is Rt above 1?

2) Are cases/100k above 10?

3) Is test positivity above 5%?

4) Is ICU usage above 85%

If any of those are on the wrong side, I'm limiting my social gatherings.

disagree.

i’m in singapore right now, with one of the highest vaccination rates in the world (82%+) of moderna and pfizer.

restrictions are still in place, and r(eff) is > 1 the last few weeks.

Not sure what the counterpoint is? r(eff) would surely be higher than it is now, if not for that vaccination level.

So you're not getting vaccinated and you've convinced yourself it's for pro-social reasons. Misinformation truly is something to behold.

The poster is confirming that vaccine mandates work as well.

Let's be clear, mitigations were being removed when vaccination rates were increasing and hospital rates were decreasing. It's only because a significant enough portion of the country has decided that not getting vaccinated is more important to them and have caused our medical system to be put back under strain have the mitigations been put back in place.

80% of people 12 and up have received two doses of Pfizer or Moderna in Canada. COVID is still a major factor here (worse than ever in some regions with lower rates ~75%).

[1] https://www.ctvnews.ca/health/coronavirus/more-than-80-per-c...

And how many of the people effected by that are unvaccinated? You are simply re-stating what I said, as vaccines rates went up AND hospitalizations went down, mitigations were removed. Then the Delta variant hit and has been an absolute disaster for those who have refused to get vaccinated and our medical care system. 20% is a significant amount of people, and hospitalizations have gone up and therefore mitigations have been put back in place.

I would love to get back to (semi-)normal, I'm sick of this shit. But I've done, and continue to do the things that are helping make things less worst, I wear a mask, I socially distance, I have my vaccine. If a new version of the vaccine came out that targeted the Delta version of Covid, I would get that too.

And I don't believe that Covid is going to be eradicated by everyone getting vaccinated. In fact, I don't know anyone that believes that. What I and others believe is that if we get very close to 100% vaccination, we can lift many of the mitigations being put in place.

Yes, people will still get Covid, but they will be less likely to get it, less likely to get sick if the do, less likely to have severe symptoms, less likely to go to the hospital, and less likely to die. And our hospitals won't be over run.

The main purpose of my comment was to add some clarity to the discussion with concrete numbers and references. Terms like significant, insignificant, less, more, etc, should be quantified with references in my opinion where possible.

To answer your question, the unvaccinated represent 75% of hospitalizations in one region that publishes raw data (https://bit.ly/3oriNqS).

It's that and that the more spreadable Indian/Delta Variant developed and took hold in April. (Variant name there for news references) Took the US 2 months to announce it was a concern.

So is measles, polio, & chickenpox, but those vaccines have still made a huge difference in general quality of life.

You should still get vaccinated. Post-infection immunity is very heterogeneous, with respect to what level of protection you'll have, and how long it will last. You might have great protection for a bit, or you might get reinfected just like the first time, like many have.

The combined protection of natural with vaccination will be better than just one or the other. I hope you stay safe.

an israli paper claimed my immunity is 13 times better now compared to vaccinated people.

The CDC says[1]

> Yes, you should be vaccinated regardless of whether you already had COVID-19 because:

> Research has not yet shown how long you are protected from getting COVID-19 again after you recover from COVID-19.

> Vaccination helps protect you even if you’ve already had COVID-19.

an Israeli paper[2] (probably the one you're thinking of) also mentions that yes - your immunity from having the disease is better than a vaccine but getting both still provides a much better outcome. Please note that this study is very recent and may be overturned in review.

> This study demonstrated that natural immunity confers longer lasting and stronger protection against infection, symptomatic disease and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity. Individuals who were both previously infected with SARS-CoV-2 and given a single dose of the vaccine gained additional protection against the Delta variant.

So maybe you'll end up super-immune! Congratulations! (now go get vaccinated)

1. https://www.cdc.gov/coronavirus/2019-ncov/vaccines/faq.html

2. https://www.medrxiv.org/content/10.1101/2021.08.24.21262415v...

What's the paper?

I'd guess it's this one: https://www.medrxiv.org/content/10.1101/2021.08.24.21262415v...

It's been recently published and the warning on it is:

This article is a preprint and has not been peer-reviewed [what does this mean?]. It reports new medical research that has yet to be evaluated and so should not be used to guide clinical practice.

It's not something that can be held up as evidence in any direction at the moment.

FWIW, an anti-vax cousin of mine has had covid three different times. Each time he recovered, but each time he kept spreading it. So don't count having had covid once as a blanket "I don't need the vax" card.