Previous Covid-19 may cut risk of reinfection 84% | Hacker News Reader

Previous Covid-19 may cut risk of reinfection 84%

cidrap.umn.edu

110 pointswalterbell116 comments

With such a tiny number of confirmed re-infections from a virus that has been around for over a year, it seems pretty clear that natural immunity works very well and lasts a lot longer than many people feared. The various vaccine makers have all been very vocal that their vaccines would elicit an even more robust and longer-lasting immune response. I suppose that's what we would expect them to say, but they must have some science behind those predictions.

The emergence of a second wave of infections in Manaus, Brazil, despite an estimated 76% of the population having acquired antibodies in the first wave, would seem to pretty conclusively demonstrate that a natural immunity strategy (or an emergence of natural immunity in the absence of a coherent strategy) (a) did not work well for the people and (b) provided an incubator for new, more dangerous strains to evolve.

https://www.thelancet.com/article/S0140-6736(21)00183-5/full...

Every time this has come up I’ve seen people point out that there were methodological problems with the study that found such high seroprevalence, and that plus the fact that there’s still few actual concrete documented reinfections - even as the P1 variant has spread around the world - or the fact that there’s no evidence P1 escapes any of the vaccines designed for wildtype (of course, the immune system is complicated!), at least points in the direction that there never was a 76% infection rate in Manaus.

You can always quibble with the exact percentage (and the article I posted discusses some of the objections), but there is considerable evidence that there must have been a fairly high infection rate — given the minimal measures taken, there hardly is another explanation for why the first wave petered out and case numbers stayed low for several months. Excess deaths in the first wave were .15% of the population of the city, which is relatively young, which also points to a high infection rate.

And all of that didn't help one bit in the second wave.

A year ago, many people took seriously Swedish claims that Stockholm was close to herd immunity. Now Manaus is never supposed to have reached herd immunity levels. It seems to be a bit of a "No True Scotsman" type of situation.

Take a look at this: https://web.archive.org/web/20210204143915/https://www.novav...

Go to slide 28.

This is Novavax's presentation of clinical trial results. As part of their phase 2 trial in South Africa at the end of 2020, they gave everyone antibody tests. In the placebo arm, 30% of that arm was seropositive (had antibodies from a prior infection). Of the seronegative group, 2.9% contracted COVID during the study. Of the seropositive group, 2.9% contracted COVID during the study.

At the time, most infections in SA were the B.1.351 variant (referred to in the presentation as 501Y.V2). This variant has many of the same mutations as P.1 and is believed to have a similar ability to evade immunity.

I'm sorry - a preliminary trial for a vaccine that's not currently in widespread use being ineffective against a different variant makes a pretty flimsy case for the danger of reinfection with P1.

And actually, Novavax later announced that actually, natural immunity does provide protection against the SA variant [1]:

> A previously reported initial analysis from the study through 60 days indicated that prior infection with the original COVID-19 strain might not completely protect against subsequent infection by the variant predominantly circulating in South Africa. However, the complete analysis of the South Africa trial indicates that there may be a late protective effect of prior exposure with the original COVID-19 strain. In placebo recipients, at 90 days the illness rate was 7.9% in baseline seronegative individuals, with a rate of 4.4% in baseline seropositive participants.

Moreover: the SA variant and P.1 aren't necessarily similar in terms of immunity evasion. For instance: SA isn't using the AZ vaccine at all because of how ineffective it is against their variant, but it works just fine against P.1. Or look at this paper [2]:

> Neutralization titres against P.1 were similar to those against B.1.1.7 and only a minority of samples failed to reach 100% neutralization at 1:20 dilution of serum, considerably better than neutralization of B.1.351, where titres were reduced 7.6-fold and 9-fold for the BNT162b2 Pfizer and ChAdOx1 nCoV-19 AstraZeneca vaccines respectively.

[1] https://ir.novavax.com/news-releases/news-release-details/no...

[2] https://www.biorxiv.org/content/10.1101/2021.03.12.435194v1

I'm not talking about the vaccine aspect of the trial, just the placebo arm where they did the antibody tests. I hadn't seen their 90 day update, so thanks for that.

Your original statement that there were few documented reinfections. They found 30 of them here under controlled study conditions, and prior infection provided less than 50% protection against B.1.351.

To my knowledge, there hasn't been a controlled study like this in Brazil. The in vitro results you cited suggest that while the immune escape of P.1 is not as great as B.1.351, it still is very substantial, and reinfection will occur in a substantial number of patients.

Per the Washington Post just two days ago [1], there have been just 71 confirmed reinfections worldwide, which is why I made that claim. Unless half of those came from that study, I’m not really sure how to square this.

I disagree with your assessment of P.1 immune escape being “very substantial” based on those in vitro results. It’s on par with the UK variant, which has no evidence - real world or otherwise - or reputation at all for widespread reinfection or vaccine escape. Never mind that in vitro results don’t even tell the whole story of an in vivo immune response. To be perfectly honest, I’m struggling to see how you’re making that claim.

[1] https://www.washingtonpost.com/business/can-you-get-covid-tw...

Washington Post cited BNO news, which is just one guy I believe. I don't know if he's just sourcing these from news stories or what. If they're seeing 30 reinfections over 3 months in 650 study participants, you can be quite sure that there are a lot more than 71 reinfections in the world.

There is no evidence of widespread reinfection in Manaus.

There's some evidence, as explained in that article. It's just equivocal, as is the evidence in most COVID-19 studies, even the strong studies. Unlike most studies, though, neither the above nor the original study showing Manaus seroprevalence seem easy to dismiss. For example, the reinfection study notes that the elapsed time before the first wave and second wave was greater than the period of immunity established by other studies.

Definitely something to keep an eye on.

Natural immunity is not free. A lot of covid patients have suffered long term damage to major organs.

Source for the "a lot" part?

Yes. Contrary to what the talking heads want people to think, getting natural immunity to COVID by allowing your body to fight it off with its own defenses is a totally legitimate way to navigate this pandemic.

No, it’s not a very legitimate approach to suggest for most folks. Sure, you have a right to do that yourself, as long as you don’t infect anyone else. But the negative long-term side effects are risky enough that it wouldn’t be good to suggest that most people try it. Additionally, the reason it was not suggested by the “talking heads” was to avoid people infecting their elderly relatives, who are much more likely to die.

You’d have to have pretty definitive evidence to suggest that getting COVID is equivalent to getting the vaccine in terms of positives. The cons of getting COVID itself are way worse for most people than just getting the vaccine.

https://www.cdc.gov/coronavirus/2019-ncov/long-term-effects....

> The cons of getting COVID itself are way worse for most people than just getting the vaccine.

How can it be worse for most people if most people don't even notice it and that being one of the reasons why the virus spreads quickly? People mention infection's side-effects, yet no one was screening those with side-effects prior their infection to definitively establish causation.

Most people do notice it. The real problem is that most people don't notice it until after they've been spreading it for a couple of days.

Hard to say. There are tons of studies on the subject and they all have different findings. The number of asymptomatic covid positive people who got tested was found to be between 5% and 90% (not talking about pre-symptomatic, aka people who developed symptoms in the next weeks).

There seems to be a correlation with age, the younger you are, the less likely you have symptoms.

Considering that asymptomatic people are less likely to be tested than people with symptoms, this is a lower bound.

I'm inclined to believe the majority of cases are asymptomatic and that therefore that most people don't notice it.

Definitely a lower bound. In reality cases have probably been several multiples higher (and mortality rate several multiples lower).

Not most people, but Death isn’t worse?

Fair point, but it must be added that it can be valid only as long as one understands and accepts the risks and possible consequences (including the social factors), and doesn't spread it further to anyone without their full awareness and explicit consent.

> and doesn't spread it further to anyone without their full awareness and explicit consent.

Agreed, but which is impossible to actually control.

If you just get it through exposure at an unknown time, then you are potentially exposing vulnerable people during the contagious part of the pre-symptomatic period.

If you are talking about controlled deliberate exposure and managed isolation afterwards (and I guess refusal of medical care if this was prior to their protection from the vaccine) I guess that is different, except that it would also have the externality of contributing towards generating new variants and potentially breaking vaccines for everyone else if you slipped up in your isolation.

Notable commentary:

> The findings of the authors suggest that infection and the development of an antibody response provides protection similar to or even better than currently used SARS-CoV-2 vaccines.

https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

In case you wanted to know - several hypotheses float around on what provides more protection an actual infection or the vaccine.

My intuitive and 0-observation question is how in the world can a reduced function protein give you a better immune response than the full-featured, infect anywhere there's an ACE receptor, c19 infection?

('A Request for Submissions' I guess should be the title of this question)

The spike protein "springs" into an elongated configuration to help it latch onto a cell wall. Several of the vaccines have purposefully modified the protein used in the vaccine to keep it in it's unsprung form. The idea is that you want the antibody response to be focused on the unsprung protein so that you can prevent it from attaching and springing in the first place. From what I understand, the vaccine researchers have tested several variations of the spike protein in animal models to try to select one that will yield the best antibodies. The immune system is quite complex, but in theory it would be possible to design a protein that resulted in better antibodies than a wild infection. An analogy is it's like showing your immune system a lock and asking it to come up with a key that opens the lock. A different lock might produce a universal key that opens many locks.

Total load, and immune stimulation can be different between infection and vaccine, as unintuitive as that might be.

And many viruses, SARS-Cov-2 included, have immune response suppression effects that the vaccine does not.

More study is needed, both those are possibilities.

Surely, I guess that's kind of the point right? You hope to 'smoke out' a response with much more load of a milder substance, rather than send dangerous amounts of fully active c19.

The question I have is, I get that the 'spike proteins' are important, but isn't that just the entry mechanism, and not the complete picture of a c19 infection pathway - i.e. the nature of the c-storm and how effectively the Krebs cycle destroys itself because of what happens after c19 enters the cell?

The above is a terrible memory dump of the video below: https://www.youtube.com/watch?v=Aj2vB_VITXQ

Still a lot of work to be done, what I do know is, I have a family member who went to a friends party and got infected, he was sick for a few weeks and recovered without hospitalization. A few months later, the genius decided to go to a Casino near Reno NV and got infected a 2nd time and was just as sick.

I look forward to returning to a time when catching a respiratory virus is an act of nature and not a moral failing.

Pre-pandemic I had a habit of chucking visibly sick people out of the classroom. No one needs whatever bug they are spreading, not me, not their classmates. This attitude of presentee-ism needed to die even then. We hope it's dead now.

I once had a teacher in school who got mad at me for daring to take a sick day. As a moral tale, he explained that he taught class even when he had a slight cough, which turned into pneumonia. This was to show how dedicated he was. Whereas I, a high schooler, was thinking, "Doesn't that mean you SHOULD have taken a sick day, so you wouldn't have progressed to pneumonia?"

If we get anything positive out of Covid, I hope it's as you say, the cult of soldiering on while infecting others has stopped.

Presentee-ism needs to die full stop.

There is no reason to force another human being to attend your lesson if they can pass your exam / go to work if they can deliver the same results somewhere else.

(I'm not advocating for forcing employers and school to give people flexibility through legislation, I'd just want to see a voluntary cultural shift)

I do hope the moralizations get cut back but also that adults and children stay the fuck home when sick and we can ditch this perfect attendance play through the pain attitude towards minor infectious diseases.

Agreed.

I also hope that some stigma of knowingly going out into the world while sick persists. Probably won’t, though.

Leveraging a historical perspective (not a judgement about "good" or "bad" or "should" or "shouldn't", just an observation), the world really might not return to accepting a respiratory virus as an act of nature.

For example, dumping fecal matter into streams was the norm (still the norm in many places today). Arguably it was and is still considered "an act of nature". However, the modern appetite for such behavior is considered unethical/immoral (unless left with no other options).

This story regarding personal and group health vs personal freedom and choice (or ignorance through accidents/neglect) repeats many times in history. Arguably each article of clothing was at one time a unique and major health/wellness conversation within the culture, and either won out or that clothing was lost to time. Similarly in home plumbing (a home without running water is considered immoral), contributing towards smoke/smog in cities is considered immoral, etc.

It seems likely that both masks, and accidentally getting a respiratory virus (including the cold/flu - given its death toll) could flip into the immoral bucket forever regardless of the impact to "personal freedoms". I'm not smart enough to know which way it will go or which way it should go.

Which ever way it ends up falling, I hope we come out with a healthier society for our bodies, but also for our psyches.

Not so long ago, like in the 80's, smoking was acceptable nearly everywhere. It was fine if you didn't want to smoke, but if you asked somebody to, say, not smoke right next to you, or not smoke in your car, you were considered to be the one with a character flaw, impinging on their "rights" and "freedom."

It's interesting how things change.

the difference of course is that it that, unlike handwashing or dumping fecal matter in the water, there is still no scientific evidence that masks actually work (for reducing infections when worn on the street by a population where most people are not infected)

no seriously - I wish I were kidding!

I feel like that's misleading. The key thing you said is outside - inside there is plenty of research about various aspects of the protective value of masks in stopping droplets and comparisons of various masks. https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-re...

If you study the scientific literature for works that measure actual infections with/without masks (and not hypothetical scenarios on droplet travel distances) you'll find that the science is far from being established.

Take a look here just how many works indicate no effect:

https://swprs.org/face-masks-evidence/

These may be cherry picked of course - no question there, still it is evidence that the science is not settled.

For a "home-run" review see the Cochrane review:

https://www.cochrane.org/CD006207/ARI_do-physical-measures-s...

Not even N95/P2 respirators were found to be effective.

Did he actually get tested for covid both times? There's plenty of other illnesses that'll make you plenty sick. I personally took a few weeks to recover fully after the flu a few years back.

> took a few weeks to recover fully after the flu

"But it's just a flu"

The number of idiots who think the flu alone (let alone COVID) is a mild thing...

Yes, he had to for work reasons.

As you say, sars-cov2 viruses come with all sorts of epitopes that could conceivably generate immune responses, and the sense I get is that with real infections, there's an element of chance as to which ones generate responses, and they're also not all created equal in terms of which ones tend to be conserved vs. vary a lot among strains. The choice of the spike protein for the vaccine was specifically to generate responses to epitopes that are thought to be highly conserved (though not perfectly, given e.g. B1351), whereas with natural infection you might generate a response that successfully clears your current infection but might be less protective against the next version you encounter.

(Though at 84%, maybe that effect is weaker than some speculated it might be?)

AIDS. Some infections never result in practical immunity. Ebola. Some diseases are so lethal that survival of infection isnt a real option. In these cases any reduced function protien would be better than infection.

This is kind of assuming that a vaccine is in fact possible with these diseases...

HIV vaccine is in the works: https://www.europeanpharmaceuticalreview.com/news/141892/nov...

I think we have it for Ebola, at least? https://en.wikipedia.org/wiki/Ebola_vaccine

Huh, TIL. Only in the past year or two, though, so I don't feel too bad about it.

Yay, science!

the way I understood it, against a living virus there are different types of responses, some more effective than others, the duration and effectiveness of the protection may depend on which response your body mounted

whereas with the vaccine there is more control over which response is being triggered

Being sick, especially recently, makes you less healthy and more susceptible to all kinds of viruses?

One interesting thing here is that this is working against selection bias.

That is, if you have had it then you start out susceptible to it. So the cohort studied for this number may differ from that studied for vaccines studies, particularly those performed selectively on people who have not contracted covid.

Of course, I'm assuming here that people have different likelyhoods of contracting the virus given similar exposures. That seems reasonable but I don't know how large the effect is.

Could go the other way too. Having had COVID with some strong symptoms can make you more prudent as you might fear to get infected a second time.

Possibly sometimes, but anecdotally that doesn’t seem like the normal direction it goes. Of the folks I know that have had it they’ve become much more likely to take risks on the assumption that they “got it over with” and would probably have resistance afterward.

“I had it six months ago”

“I had it at the beginning”

My experience matches your experience with other people

Of course I haven't run into the other people who are out, have had it, and aren’t leading with that

So we wouldn't know

Its like the silent vegans that prepare their meals and you just don't notice. They're out there, in theory.

I had it near the beginning and it was terrible. Should have been in the hospital. Did not go for a number of reasons, and a big one was capacity and isolation. Early treatment was rough too.

My fam ended up with it. Was early enough we just did not do what we needed to do. So we all were down for that month.

Outcome?

Ended up being ultra conservative about it. Still am. Older people in my life are at risk. And our symptoms were no joke. Mine were the worst of the family.

That said, my experience is similar. I see way more people failing to be at least prudent about it.

Many just do not want to be bothered, and or feel strong motivation to grab onto any rationale that can keep them active.

I don't blame them. The lock down really sucks.

I would assume that you also have the luxury of being more careful.

If one can work from home, has no children in public school, lives in the sticks and restricts themselves to necessary trips to the grocery store only, then your risk of getting it is rather lower than if your work is 2 minimum wage jobs with lots of customer contact (say you work at a grocery store in a densely populated part of a large city etc.), you have to take public transport across town to get there because you can't afford a car and your kids are at a public school in the worst district with huge class room sizes and less than ideal 'clientel'.

Absolutely true. So many are unable!

That's a big contributor to why I won't blame people for playing it differently.

That is, if you have had it then you start out susceptible to it.

That implicitly assumes equal opportunity for exposure for everyone. This seems rather implausible.

You have to be exposed to it to get it. Lifestyle influences who gets exposed.

Not that surprising, that’s how immune systems work.

More surprisingly, it looks like some of the vaccines might provide even better protection than previous infection.

Is that surprising?

The virus is specifically evolved to avoid immune response.

The vaccine is specifically designed to trigger strong and lasting immune responses.

Both statements are wildly inaccurate.

Why are they inaccurate? Not trying to be snarky, just understand what you mean.

The second one, at least, is wrong in two ways: The vaccines development was focused on reducing symptoms, and we don't know the limits of how long vaccine or natural immunity will last, simply because neither has been around that long.

Last I remember reading, both are "for as long as it's been studied so far" - 8 months for natural immunity, 3 months for the vaccines. These numbers will increase as we continue keeping track of it to see how much the effect degrades over time.

Firstly, we have a lot more than 3 months of data now. This study of the Moderna mRNA vaccine shows that after 209 days "antibody activity remained high in all age groups" and and "nearly all participants had detectable activity in a pseudovirus neutralization assay".[1]

Secondly, sure, we don't know how long vaccine immunity will last, but that's a far cry from saying that vaccines were not designed for lasting immune reponses. For example, Pfizer/NTech's phase I/II trials explored over different doses, and they ended up selecting a dose of 30 micrograms rather 10 micrograms or 1 microgram because 30 micrograms elicited greater antibody responses, sustained over their measurement period of 43 days.[2]

Thirdly, quoting from the abstract of that same Nature paper: "Two doses of 1–50 μg of BNT162b1 elicited robust CD4+ and CD8+ T cell responses and strong antibody responses, with RBD-binding IgG concentrations clearly above those seen in serum from a cohort of individuals who had recovered from COVID-19." [2]

Let me state it again, without the jargon: Vaccinated patients had antibody responses clearly above those who had recovered from COVID-19. This, as I understand it, is why the CDC recommends that those who have recovered from COVID-19 still get the vaccine, as it offers extra protection from weaker or faded immune responses. [3]

Do you really think my statement that 'the vaccine is specifically designed to trigger strong and lasting immune responses' is wrong?

As I shared above, the phase I/II trials of these vaccines measured time series of immune responses to help select the dosing, and they picked a dose that had a strong immune response that lasted over their measurement time series.

[1] https://www.nejm.org/doi/full/10.1056/NEJMc2103916

[2] https://www.nature.com/articles/s41586-020-2814-7

[3] https://www.cdc.gov/coronavirus/2019-ncov/downloads/vaccines...

- The virus is not designed

- All viruses evolve to avoid immune responses

- The default assumption until we get new evidence should be that COVID-19 behaves like a Coronavirus, where immunity is relatively long-lasting

Pardon the nit-pick but it's more accurate to say: Virus' variants that avoid immune responses persist.

That is, effectively, to evolve is reactive, not proactive.

Does anyone have thoughts on why there are so few documented reinfections if the risk is only cut by 84%? For instance this tracker only has 71 cases: https://bnonews.com/index.php/2020/08/covid-19-reinfection-t...

If it's that subsequent cases are much less severe then the 84% figure may be significantly understating the protective effect of natural immunity.

Perhaps a localized form of herd immunity?

If people are getting it mostly from close contacts, maybe it already ripped through these little populations (families, small workplaces, etc.) pretty well.

It could be that the body is able to fight off the infection better, so they only have mild symptoms. Maybe they don't even know they have it again. The data in this study was based on health care workers who were tested every 2 to 4 weeks (i.e. not just when they felt really sick).

Can I get a card that says I already had it and I am good to go? I even have the time off work to prove it! I am involved in a study that is measuring antibodies and 6 months later my antibodies are still really high.

I'd prefer to live in a world where I'm presumed healthy until proven infected/toxic/contagious. I'd rather not to see yours or anyone else's card.

The unfortunate downside of your approach which has proven to be so deadly for us with COVID is when you’re spreading it without symptoms for many days. If our goal as a society is to ensure most people stay healthy and alive, perhaps yours is not a good approach in all cases.

The goal of our society is to allow people to live their lives in freedom - as they wish.

Constraining society to pander to those who are essentially scared of their own shadow and are clearly suffering from irrational anxiety and borderline paranoia is not acceptable.

It is way past time that those who are scared started to pay the full cost - which means they get to stay out of the way while everybody else gets on with their lives. They cannot be permitted to socialise that cost onto everybody else.

Once we have a vaccine, and in sensible countries public healthcare free at the point of delivery, that is as much insurance as society can offer. If you're still scared after that then, as the young tend to say these days, that is a 'you' problem.

The young don't say it's a 'you' problem anymore: now they want legislation to fix everyone else.

This pandemic is just one more step in the same direction.

I blame education for indoctrinating the last generations and society for forcing parents to overwork and not be present at home to fix this mess.

How about we wait and see if, after everyone who wants a vaccine has gotten a vaccine, COVID is even still a going concern before we decide that it's a good idea to start keeping a permanent, centralized log of everywhere every person in the country has been (which is what most of the vaccine passport proposals I've seen have been).

Given the mortality rate (roughly on par with 2003), I wouldn't say it proved to be "so deadly".

On top of this, a lot of the people who died were already vulnerable, so we will likely see a downtrend on elderly deaths in the next years (all the people who would have died in 1-5 years for other reasons but died now because of covid).

Sure, a lot of people died but I don't think it warranted 2 years of isolation and aggravating the already dire financial position of millennials.

Our goal as a society is not only to ensure most people stay healthy and alive; we could just put everyone in confinement cells for the rest of their life if we wanted that.

I think our goal is to balance that with what people desire are.

I'd happily take a higher chance of dying to live the free life I want.

> If our goal as a society is to ensure most people stay healthy and alive, perhaps yours is not a good approach in all cases.

Prior to COVID-19, we used to be able to acknowledge that we make choices every day that do not maximize the number of healthy and alive people, yet we made them anyway: both on a personal and societal level.

That's because maximizing the number of healthy and alive people is not the only goal of society.

> If our goal as a society is to ensure most people stay healthy and alive, perhaps yours is not a good approach in all cases.

Most people are not under a risk, it has 99% survival rate

> Most people are not under a risk, it has 99% survival rate

In my circle, there's a friend who has lost his sense of taste and is immensely depressed about losing the ability to tell the difference between steak and spam.

He can still taste sriracha, but he is nearly suicidal from this (partly regret for taking risky decisions).

Survival isn't the only measure of impact.

Losing sense of taste can also be a early sign of depression.

I had that (long before covid) sign and it gradually improved as I fixed up my life.

Wishing the best to your friend but I would give him hope.

I have a friend who got recently diagnosed chronic fatigue syndrome and I doubt that's attributable to covid.

I'm very skeptical of long covid claims, I think those are most likely just side effects of the social experiment we just run, socially isolating the entire population and stressing them out for a year.

> He can still taste sriracha, but he is nearly suicidal from this (partly regret for taking risky decisions).

if survival isn't the only measure, then the same principle could be applied to suicidal feelings of so-called "non-essential" business owners who lost their livelihoods and years of savings during the lockdowns. One could argue that a sense of taste isn't "essential" either.

When you travel outside the US and are coming back you either need to have a Covid test within three days of return or show proof that you already had it. So yes, you can get documentation from your doctor that you already had it.

There seems to be the intention to lower incentives to be infected, and to raise incentives to get vaccinated.

Therefore, the party line seems to be to dismiss natural immunity.

I think the talking points will change once all 50+ people in the west are vaccinated.

I’m in your situation but I got the Pfizer vaccine anyway. I think it made me feel good (look up long haul vaccine improvement) even though I didn’t feel like I still had symptoms. Cheers

I took a placebo and feel great!

Nothing wrong with taking a placebo. It works even when you know you’re taking one.

It would be interesting to study whether placebos stop working if you forget to take them.

Schroedinger’s placebo

They do. People who take their placebos do better than those who don't .

Side effects can be a problem.

It’s a really small survey so far but roughly 2/3 of covid long haulers saw improvement after vaccination. 1/3 didn’t. I’m curious what actual, rigorous, studies will show later of course.

That study raised some... questions... because many of the self-proclaimed "long haulers" had never tested positive for COVID.

Which is of course possible, but it also raises the specter that "long-haul COVID" is really a mask for (understandable) psychological stress and depression which not-coincidentally coincided with pandemic and lockdowns.

You won't see much clash on this comment because the evidence for long covid is poor. Incidence rates mirror hypochondria rates and symptoms are explainable by things like vitamin D deficiency and depression.

This study shows long-COVID-19 is real.

https://jamanetwork.com/journals/jamanetworkopen/fullarticle...

What evidence do you have these are caused by vitamin-D deficiency? What are the incidence rates and how is it the cause?

The most commonly reported symptom was fatigue.

Chronic fatigue syndrome is treated primarily with Cognitive Behavioural Therapy.

It's absolutely compatible with mental illness, especially considering that our governments just locked up everyone for more than a year.

At any rate the CDC mentions they have multiple multi-year studies underway so we won’t have to guess. https://www.cdc.gov/coronavirus/2019-ncov/long-term-effects....

Nope. Because you might get a variant you’re not immune to. Even those vaccinated that may happen to.

Not to mention people who develop an immune response but not one robust enough to stop another infection.

If folks think getting Covid or the vaccine is the end of things will be surprised. This isn’t going away in the next 3-4 years.

There was another study that suggested however that previous COVID-19 wasn't as effective against variants and that that was one of the root causes of the current Brazil situation (many reinfections).

This might sound like a dumb question, but does anyone know if COVID is a bit like the common cold in the sense that you get a different variant every time you contract a cold? So having had a cold before is a near guarantee that you won't get the same cold, but almost no protection against a different cold.

Colds are a bit different because of how many different viruses cause them. SARS-CoV-2 is still a single virus for some definitions of "single" and "different."

Is it appropriate to compare this 84% figure against vaccine efficacy? If so, it’s quite amazing that artificial vaccines can be more effective at providing immunity than infection with the actual pathogen.

Not unusual, look at tetanus. The tetanus toxin is so potent that the amount that can kill you isn't enough to generate an immune response, so even if you manage to survive there's no guarantee you won't get it again as you'll have no protection. The vaccine on the other hand generates a much stronger response than the real disease.

Note that the tetanus vaccine actually targets the toxin itself, not the bacteria that produces the toxin: https://www.who.int/biologicals/vaccines/tetanus/en/

Anyway, it's a myth that you can't develop antibodies to tetanus/tetanus toxin naturally. Lots of studies have found otherwise, finding tetanus antibodies in both humans and animals that haven't been vaccinated: https://pubmed.ncbi.nlm.nih.gov/1092755/

It's just not a very relevant fact, as tetanus is deadly, and the tetanus vaccine is cheap and works well. In fact, there's evidence the vaccine works even better than we thought, and booster shots may not be needed: https://academic.oup.com/cid/article/72/2/285/5741633

Except that the COVID19 vaccines don't work at all in the same way at the tetanus vaccines.

Uh... yes it does? Both present an single inactive/non-dangerous molecule to the body against which it can develop an immune response using its own toolkit. Tetanus toxoid is synthesized externally where the covid spike protein is done by the body via introduced mRNA, but the immune system is doing the same job.

So they're the same if you overlook the tiny detail of where the antigen is manufactured, either via a totally novel method in the body via instructions encoded in mRNA versus synthetically in a lab somewhere.

Yeah totally exactly the same 9.9

Sigh. The question was about why it should or shouldn't be surprising that a vaccine generates a stronger immune response than a real infection. And tetanus was cited as an example. And it was dismissed as being unrelated. And that was WRONG, because the immune mechanism is basically the same and the only difference is where the antigen comes from.

To wit: tetanus and covid vaccines both generate stronger immune responses than the virus they are designed to fight, and for very similar reasons. Do you actually disagree with that statement?

> it’s quite amazing that artificial vaccines can be more effective

It's the other way around

> The findings of the authors suggest that infection and the development of an antibody response provides protection similar to or even better than currently used SARS-CoV-2 vaccines.

The latest data is that the vaccines are about 90% effective after the appropriate waiting periods.

Do covid test detect past infection too or not ?

Antibody tests are designed to have low false positives, not low false negatives.

And blood samples have found that a proportion of samples have t-cell immune responses to sars-cov-2 without antibodies, possibly with no exposure to sars-cov-2 specifically.

Specific antibody levels drop after a few months.

Therefore, might be impossible to establish if someone was exposed or what level of immunity.

There are specific tests that try to detect past infection, but the general standard tests will only detect current infection.

Well, I mean, can't be re infected unless you've been infected at least once before, so 100% of those reinfected had it before.

Umm, duh. Has the whole world suddenly forgotten 9th grade biology these last couple years?

Yes, they did. Remember how the existence of T cells, memory cells and literally the entire immune system aside from antibodies was treated like a new discovery?

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