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Alwayssunnyinarizona t1_jdiozcj wrote

It's a bit like asking if the wooly mammoth could come back.

Delta has for practical purposes "gone extinct", out competed by other, more successful variants.

At this point, it may only exist in a lab setting, where it could in theory be resurrected. It's only chance to persist really is with a little human help because more competitive strains are still out there on the landscape.

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porkypuha t1_jdirgk3 wrote

Are the current strains way less contagious? I lead a life that should make it really easy for me to contract the virus but I still haven’t caught it. I test myself whenever I slightly suspect I may be infected.

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Alwayssunnyinarizona t1_jditzmk wrote

The most common strain in the US currently, omicron xbb 1.5, transmits better than previous strains - the virus would die out if it didn't. There's the pressure exerted by herd immunity, but if the viruses didn't transmit more efficiently, they'd die out.

I also lead a life that should make it really easy to get infected, but the vaccines continue to work. There's a high chance you've been exposed and the infection was so mild you didn't even notice - either because you were vaccinated or immunologically lucky.

I'm also a bit surprised, as when something has been in the news - RSV or norovirus, for example, we've already had it a week prior (kids in daycare/school), so we're certainly at high risk of exposure for something like covid. All I can say is that the vaccines seem to be working.

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Matrix17 t1_jdj5svb wrote

What's the current guidance on how often you should get boosted?

Girlfriend and I did in the fall, then at Christmas we both got sick but only she tested positive. So I dont know if I should be waiting a certain time after that

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Alwayssunnyinarizona t1_jdjaqo7 wrote

There's no real specific guidance, but it's starting to turn into more flu-like guidance - vaccines recommended every year around the same time you'd be getting an annual flu vaccine, regardless of whether you were infected in the last 6-12 months or not. Expect there to be additional combo vaccines this fall (flu/covid), and that may persist for years until/unless covid starts to fall below background common cold status.

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Matrix17 t1_jdjfkq1 wrote

Yeah I hope it becomes a combo vaccine. Since the uptake now is low, it might boost the numbers a bit. But the same people who won't take a covid vaccine are probably the same that won't take a flu vaccine. And it's not like flu vaccine numbers are high to begin with

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SwimmingWonderful755 t1_jdjqc1q wrote

(New Zealand) I was recently part of a medical trial relating to getting a covid vaccine at the same time as, or 6 weeks after a flu jab. Pfizer funded, double blind, decent sized pool, one of many countries participating, tra la. Results aren’t available publicly yet, but work is being done on the viability of piggybacking them, at the very least.

Anecdotally, I had covid and flu jabs at the same time (soreness at the site etc (and later confirmed when unblinded) and placebo at 6 weeks, no reaction more than swelling at the injection site. Chatting with others in the waiting room, sounded like it was similar in our cohort, at least.

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MidnightAdventurer t1_jdkcgs1 wrote

The latest booking system on the NZ MOH website gives you the option to have both at the same time.

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SaltConfiscation t1_jdkbsti wrote

So it would behoove one to wait until the fall at this point? I was meaning to get boosted last fall but wound up missing it, but I'm unsure what to do. Official guidance always says to get it of course, but is that really worth it?

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Alwayssunnyinarizona t1_jdkebp9 wrote

That'd probably fall under the category of giving medical advice. There may be an updated vaccine in the fall, I'm not really sure how that will play out.

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drunkenknight9 t1_jdje7kd wrote

It's not about the number of cases out there but rather the severity. If everyone is getting covid but no one is getting sick enough to die or need intensive care, there won't be a need anymore for a vaccine. The natural life cycle of any virus is for it to become more infectious and less dangerous to the hosts since that's the best way for the virus to survive. The multitude of viruses that cause the common cold have already undergone that evolution. Influenza is a very unique case because of the structure of the virus that allows recombination among and between strains from different species means novel flu strains can happen any time without much warning and our immunity can be very variable. There are other outliers like HIV but most viruses that have ever infected humans have become relatively inert. A great example of the most extreme form of becoming inert is JC virus which is entirely asymptomatic and inconsequential unless someone is prescribed certain immunosuppressive medications. If you do get put on one of those medications you have to be tested for it otherwise it can reactivate and cause progressive multifocal leukoencephalopathy which is almost universally fatal.

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Matrix17 t1_jdjfvml wrote

The only issue with that approach is long covid is still a thing even in mild cases, and we still don't know enough about how it's caused or the best way to treat it

You can end up with similar issues with any respiratory virus, but covid is unique in that it happens more frequently, is more severe, and covid itself spreads more than the cold, flu, or other common respiratory viruses

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Alwayssunnyinarizona t1_jdjnje1 wrote

>The natural life cycle of any virus is for it to become more infectious and less dangerous to the hosts since that's the best way for the virus to survive.

That's not really true.

>As evidence mounts that the omicron variant is less deadly than prior COVID-19 strains, one oft-cited explanation is that viruses always evolve to become less virulent over time.
>
>The problem, experts say, is that this theory has been soundly debunked.

​

And in my comment, I did not distinguish case numbers vs. case severity. I said "until/unless covid starts to fall below background common cold status." I'm sorry that you read it that way.

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sciguy52 t1_jdk5p46 wrote

> The natural life cycle of any virus is for it to become more infectious and less dangerous to the hosts since that's the best way for the virus to survive.

This is a myth that gets repeated too often. Viruses sometimes become less deadly, sometimes more deadly. And many remained as lethal as always.

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Corvus-Nox t1_jdjpav6 wrote

In Canada, I believe the guideline is 6 months between boosters or after an infection.

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MaybeTheDoctor t1_jdjm4vv wrote

This is probably not a question you should ask strangers on the internet. But my belief is that I have gotten my last booster, and same is true for most people, unless they have some other medical reasons, and unless something else changes this is now just over.

We are down to a rate of 10 cases per 100000 people, so it will just slowly die out from here on, or worst case just linger on forever as a mild illness you can risk to get together with a million other mild illnesses we never cared to do much about.

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Matrix17 t1_jdk669w wrote

The numbers aren't representative though because very few are testing now and being logged

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QualityKoalaTeacher t1_jdivdcb wrote

Current dominant strains are purported to be more contagious. Like someone else said you may have caught it but just never showed symptoms (asymptomatic) which does happen in many cases.

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underbrownmaleroad t1_jdiz9i4 wrote

What an incredible mutation for a virus to attain. That has to help spread it so much

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RyanW1019 t1_jdj280w wrote

Whenever a virus replicates, there is a chance for the new virus particles to develop mutations. If these mutations make them less contagious, they will quickly get outcompeted by the old lineage and die out. If the mutations make them more contagious, they will outcompete the other strains until they become the new dominant version that new mutations develop from.

The only upside is that viruses don't usually benefit from becoming more deadly; if anything, that makes them less able to multiply if they kill their hosts. (Exception: if the host becomes very contagious before dying to the virus, more lethal strains could still develop as long as they are able to successfully leap from person to person before their victims die.) So in the long run, many viruses tend to get more infectious but less lethal, since the mechanism that makes a virus lethal is usually complicated and most random changes to it from mutations tend to reduce severity, not increase it.

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underbrownmaleroad t1_jdj3fal wrote

Very cool write up, especially learning how viruses tend to become less lethal and more contagious. It’s like the use us humans as the method for their life and once they reach their max potential it’s like oops yeah I didn’t mean to kill every one on the way

Is there any evidence that colds use to be more deadly and now they’ve reached a point that they’re largely contagious and less deadly?

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Matrix17 t1_jdj64rx wrote

> viruses tend to become less lethal and more contagious

This is not always true. Remember, there has to be some sort of evolutionary selection for it. As an example, the reason delta even became a thing, which was more deadly than the original strain, is because covid was spreading before people had symptoms. So it didn't matter if it killed the host or not, because they likely spread it before they even knew they had it. So there was no selective pressure for it to become less deadly. If covid had only spread after someone was symptomatic, it may not have turned into a pandemic at all

We just got lucky that the omicron mutation happened. If delta was still circulating, we would be in a very bad spot

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Tephnos t1_jdk6rpz wrote

> Very cool write up, especially learning how viruses tend to become less lethal and more contagious.

They don't. It's a myth that continues to be propagated because it sounds logical to the layman. It is our immunity that makes them less lethal (when we survive).

If viruses behaved this way as a given, we wouldn't have been getting killed by smallpox and many other viruses for millennia.

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yukon-flower t1_jdity8h wrote

Are you vaccinated or have you caught it previously (or both)? It’s entirely possible you’ve been exposed but your body fought it off before you could harbor enough to test positive.

We had a houseguest test positive (after previously daily testing negative ☹️), and I was definitely exposed. I felt under the weather for a few days but never actually tested positive. According to what I read in the NYT this means I successfully fought it off. I’m fully vaxxed/boosted.

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Naxela t1_jdj11hi wrote

A common rule of virus evolution is that viruses tend to evolve to be more contagious and less deadly. The rationale here is that a dead host is not a viable vector for contagion, and if your strain kills the host, then the strain dies along with the host body.

As a result, strains that keep people in contact with each other rather than isolated at home or in a hospital are going to be way more successful and will outcompete each other, and it goes without saying that of course the more contagious the virus is generally, the more successful it is as well.

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joshuas193 t1_jdivqzo wrote

As far as I'm aware the current virus is more contagious but less severe.

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Tephnos t1_jdk75gb wrote

Yes, and no.

It is less severe because everyone has some kind of immunity to it. The virus inherently is probably still as virulent as the original type to someone with zero immunity.

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azahel452 t1_jdjsqtu wrote

That's how it usually goes with virus, it's their version of natural selection. If they're too strong, they kill the host and that's not good for the perpetuation of the species, so those variations die out. The weaker but more contagious versions are the ones that have more success in reproducing. It's quite fascinating to think about.

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Tephnos t1_jdk72mf wrote

Wrong.

It doesn't matter if the host dies or not, all that matters is that it can spread before the host dies. COVID was perfectly capable of doing this via asymptomatic spread. (see: Delta).

Omicron outcompeted Delta because it had mutated so wildly that it could bypass all the antibodies the vaccines had generated up to that point, plus it drastically reduced the incubation time, meaning more spread potential. That's it. It could've been as lethal as Delta and would've still been successful.

Omicron is likely as severe as the original strain, the difference is now everyone has some kind of immunity to it, so it wasn't killing people nearly as much on a per-person basis.

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Harsimaja t1_jdkhqqm wrote

They outcompeted it by being more contagious. They are, however, less virulent (ie, less nasty should you get it). There may be a trend where these two correlate but it’s very far from a rule.

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Tackit286 t1_jdkabzy wrote

Typically viruses evolve to be more contagious, but less deadly.

Chances are you’ve either had it without realising, or still carrying some immunity from your last infection and/or vaccination.

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Demiansky t1_jdjcjzn wrote

Good analogy, but I'd compare it more to something like "could Homo Erectus come back???" The answer is "not really" because it already exists in us, today. Its like asking whether your great, great grandfather can come back.

Older versions of the virus can't come back because they've already evolved into the more modern version of the virus we see today.

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Booty_Bumping t1_jdjo2k0 wrote

Delta is not the ancestor of Omicron. Delta did not "evolve into" Omicron — it doesn't even have alpha variant in its lineage.

Another way this analogy breaks down is that humans have sexual reproduction whereas viruses are almost entirely asexual (with rare gene transfer exceptions). Neanderthal genes can enter humans because they are sexually compatible, but viruses have to rely on convergent evolution.

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Demiansky t1_jdkfryf wrote

Well, no, not every strain of the virus was on some kind of conveyor belt of evolution anymore than the hominid family tree. But all of the earlier, less virulent variants are the direct ancestors of modern variants.

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Alwayssunnyinarizona t1_jdjownw wrote

I thought about an Australopithecus analogy, but thought readers might grasp the idea of bringing back the wooly mammoth as it's currently in the news (along with the dodo). Apart from that, I've lost track of whether omicron is a straight derivative of delta, or if they have a shared common ancestor - which would make it more like the mammoth analogy ;)

Actually, according to this article in Science, it looks more like they shared a common ancestor....so, mammoth rather than Homo erectus.

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number1dork OP t1_jdit9md wrote

That's one aspect I was curious about... if the variants have to compete with each other in the same ecological niche. I would think there's enough unvaccinated people in the world that there would still be room for a new Delta infection. But does the presence of the newer, more contagious variants prevent it?

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Alwayssunnyinarizona t1_jdivhuu wrote

The viruses are racing to find people who are susceptible enough to infect. It would be like Jesse Owens trying to keep up with Usain Bolt. Jesse was fast for his time, but Usain is going to beat him to the finish line e: 99.9999% of the time - enough that if you weren't paying very very close attention, you'd never see that one time Jesse beat him. .

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florinandrei t1_jdix80n wrote

Yes. The newer variants have won the Darwinian struggle against the old variants. The old variants have been outcompeted.

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Large_Ad_3095 t1_jdk4jzs wrote

They also continue to exist in chronically infected people, mutating over the course of infections that could last years(or decades?)

These are 3 Delta variants detected this January, one of which was up to 90 mutations(and probably still mutating):
https://twitter.com/LongDesertTrain/status/1624464486596849670

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Alwayssunnyinarizona t1_jdk59ar wrote

Similar thing happens in cats with FIP, another coronavirus.

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Large_Ad_3095 t1_jdk6rj3 wrote

I never knew that! I just read that it can turn fatal due to a mutation, but do these spread in cats like COVID variants? Omicron and Delta already demonstrated that outcompeted variants can come back far worse.

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Alwayssunnyinarizona t1_jdk7931 wrote

They're typically mild infections, but some cats can be chronically infected. In those cats, a mutation in part of a specific gene can cause FIP.

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Large_Ad_3095 t1_jdk80dc wrote

Sorry, what I meant to ask is if such a mutation could go beyond the chronically infected cat and replace other FIP viruses.

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Alwayssunnyinarizona t1_jdkb53l wrote

Ah, I see. I need to read up more on feline coronaviruses, but my understanding is that the disease itself (FIP) is not transmissible per se. One cat with FIP won't give FIP to another cat, for example - it's a syndrome that is as much cat-dependent as it is virus dependent.

The coronaviruses themselves (there are various strains) are transmissible, but you need a specific mutation in a chronically infected cat to cause FIP. Once that virus has mutated, it may infect other cats, but won't cause FIP. I am not aware of any particular strain that is guaranteed to mutate and produce FIP in every (or even most) cats.

Does that make sense?

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pfmiller0 t1_jdixvik wrote

Can we say for sure that Delta doesn't exist in animal reservoirs somewhere?

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Alwayssunnyinarizona t1_jdj082m wrote

Some derivative of it likely does, but it's been eons (in viral time) since delta was first identified, so almost without a doubt it has continued to evolve in those reservoirs - much like mammoths have gone extinct but we still see their close relatives in elephants. For the time being, anyway.

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aggasalk t1_jdjqoc4 wrote

similar viruses don't really compete. you can be infected with multiple COVIDs at the same time. the older variants disappear because of mass immunity, not because of competition.

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Alwayssunnyinarizona t1_jdjvznu wrote

They are competing for resources in terms of susceptible individuals. If virus A is more transmissible, replicates in cells more quickly, or bypasses immunity that would otherwise prevent infection with virus B, then virus A has outcompeted virus B.

With evolution, everything is competition.

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Dinierto t1_jdk2fzq wrote

So what we need is a new strain of covid that can squeeze out the others but which we can easily cure, that's what you're saying

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nomnomnomnomRABIES t1_jdj2yka wrote

However the original spike is included in the bivalent vaccines. What is the scientific justification for including the spike for extinct variants?

Edit: re: u/Tephnos why are extinct strains of flu not included in the flu vaccine then?

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Alwayssunnyinarizona t1_jdj5d3u wrote

The answer is part scientific, part administrative, and part practical.

Scientifically, the spike protein is made up of many different epitopes (smaller parts of the protein that are recognized by antibodies or T cells). Some of those epitopes still convey protection for current variants.

Administratively, Covid vaccines still have to go through hoops that eg influenza vaccines currently don't, so it's easier to just use what's already gone through trials and approval processes. Soonish, the vaccines can bypass those regs and update as fast as flu vaccines do. Whether that is helpful or not is up for debate, as we've seen that flu vaccines are often outdated by the time they're released.

Practically, if the vaccines are still effective, there's not a lot of pressure on eg Moderna or Pfizer to "retool" the production lines to make an updated vaccine.

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Tephnos t1_jdk7nvx wrote

To prevent the original strains from coming back when immunity to those (eventually) wanes.

We don't want to start going backwards. Plus, there's cross-reactive immunity so that similar mutations can be recognised by the immune system without ever seeing that particular one before.

Keeping a wide breadth of spike mutations allows that to work more effectively.

Edit: u/nomnomnomnomRABIES, the reason is that Flu is an entirely different beast to COVID. Despite all the mutations COVID has gone through, it is not all that different to the original strain (which is a good reason why our immunity still holds so well). Coronaviruses do not mutate all that much, as they have the largest genome of all RNA viruses. COVID is just mutating a bunch, relatively, because of how widespread it is.

Flu, on the other hand, drifts massively, and constantly. There's no point including older strains because it doesn't help you fend off next year's Flu. Maybe once or twice in your life you'll come across a strain that is similar to one you were previously vaccinated against, which is nice, but no point wasting time cramming a Flu vaccine with all these historical Flu strains.

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