How much further can covid mutate?

[Thelm]

I’m just wondering. Is there a limit as to how far a virus can mutate? Are we going to still be in a race to contain it in five years time?

I just don’t know how this will end.

bluebird76
Because we have built up herd immunity to flu. There is a huge amount of natural exposure (gained over years and years) and therefore everyone’s got a lot of varied antibodies which can latch on all over the flu virus.
A mutation doesn’t make a massive difference.

We haven’t built this up (as a global population) for covid.

You’re going to think I’m a bit weird now, but I’m reminded of those lines from HG Wells at the end of War of the Worlds

“By the toll of a billion deaths man has bought his birthright of the Earth...”

The Martians caught Flu. Humans on the other hand had lived alongside the flu virus for millennia and over all those years, humans had built up immunity to influenza. We now have to build up immunity to this coronavirus as it becomes endemic. And yes, it will tally up many more deaths over the years, but this will be manageable.

Do I win the prize for most miserable post now?! Sorry.

everythingthelighttouches I see, thanks. There were parts of Brazil though that had built up herd immunity to covid, but then succumbed in large numbers to a new mutation. Was mortality lower in that situation, then? For countries like the UK which are v close to herd immunity through vaccination, does that mean we don't have to worry quite so much about new mutations? Or are the mutations among unvaccinated populations likely to be more deadly than might happen in a given flu year, when most of the world already have some kind of natural immunity? Apologies for all the naive questions, this stuff has been bugging me!

I like the HG Wells quote, btw!!

@Bluebird76

"flu mutates like crazy, coronaviruses mutate much more slowly."

In that case, why are we not on tenterhooks every year in case the flu becomes more deadly? I mean, we are, in that we know it's a possibility, but it's not like now with covid, where each new mutation every couple of months brings massive trepidation in case existing vaccines are totally ineffective, and in case it's much much more deadly? The timescale seems different - is it just the sheer numbers infected that is creating more, and more dramatic, mutations? Genuine question - my knowledge of virology is zero.

Well in a way, some people are on tenterhooks.

The UK has for a number of years, had a strategy for dealing with a more than serious flu outbreak. Admittedly, it's not a very good one and it assumes that even a serious outbreak won't be that bad.

What's important to note though here is the vast difference between covid and flu. Flu is a respiratory virus that rarely kills. Most "flu" deaths are actually caused by secondary bacterial pneumonia - which is treatable with antibiotics. Covid is much more than a respiratory virus - it's perfectly capable of killing all by itself and does so at a far higher rate than typical flu.

If Spanish Flu did another round, FAR fewer people would die today thanks to antibiotics.

Everything and Lijkk

You do good posts on this, I was wondering could we have clamped on this worldwide early on at not got to where we are? I think not but would be interested to hear what you think

As an aside I appreciated Sir John Bell’s take the other day (rabbit hole quote)

@ineedaholidaynow

What happened to Spanish flu?

Spanish flu was a few mutations of flu. It was an aberration - a significantly more damaging form of flu.

Once sufficient people had immunity through exposure, it was beaten in the evolutionary race by new variants which returned to the typical flu severity.

I read an article where a virologist said that there are a limited number of mutations on the spike protein before the virus loses its ability to bind to the receptors in the lungs. Frustratingly I can't find it now. I found it reassuring.

@cathyandclare

I read an article where a virologist said that there are a limited number of mutations on the spike protein before the virus loses its ability to bind to the receptors in the lungs. Frustratingly I can't find it now. I found it reassuring.

I remember that too

I sort of thought cytokine storm often caused by breakdown of lung lining (not covid virus directly) was a big reason for high C19 death toll. That's why steroids are recommended & may help (severe cases only). So like flu, it's secondary complications not the actual virus that causes most harm.

I'm more allied with lockdown skeptics, actually, Marsha, sorry to disappoint you. So not one to support very strict controls. I may be wrong. The high costs of controlling the virus & harms to young people dismay me. I'm grateful UK govts have tried hard to keep F2F learning going most of the last 16m, at least ... many countries gave up on young people. :( We've living in a giant experiment because never in history was there shutdowns of society like happened since early 2020. You can all hope my concerns about the harms from Lockdowns themselves are hugely disproportionate & misplaced. Maybe I'm thinking too long term.

As I understand, as long as the virus is circulating and spreading freely, they will keep mutating. That is why we need to get as many people vaccinated to reduce the number of susceptible people. Once we passed the threshold of % needed for herd immunity is established, the virus will slow down and it will be the end of pandemic.

@Thelm

Thanks for your replies. So what is our exit strategy then? Because I can’t go on like this much longer. Just when things seem to be getting better it feels like hope is snatched away again.

New Zealand style max suppression.

Do your best to stop it getting in with border controls and quarantine.

Keep cases low to stop it mutating into something worse, rendering vaccines useless and screening over the whole world.

If cases are imported have a robust ad effective test, trace and isolate system to nip outbreaks in the bud.

Vaccinate.

“everythingthelighttouches I see, thanks. There were parts of Brazil though that had built up herd immunity to covid, but then succumbed in large numbers to a new mutation. Was mortality lower in that situation, then? For countries like the UK which are v close to herd immunity through vaccination, does that mean we don't have to worry quite so much about new mutations? Or are the mutations among unvaccinated populations likely to be more deadly than might happen in a given flu year, when most of the world already have some kind of natural immunity? Apologies for all the naive questions, this stuff has been bugging me!“

I think I’ve been a bit simplistic in talking about herd immunity because most people are referring to immunity gained through one vaccination or infection, which speaks to the situation we are in at the moment.

Yes if everyone was vaccinated with current vaccines in one country, most of the new variants that have arisen so far wouldn’t get too far because the change is only subtle and the existing immunity might not prevent you catching it but would work enough to stop serious illness or health.

But it won’t be as good as in a few years, when everyone had had covid a few times and a few boosters (all slightly different variants) and most people have a varied arsenal of immune cells to tackle whatever comes along next.

in this thread we’re talking about longer term, I believe. Therefore, I’m talking about a herd immunity that arises from decades upon decades of exposure.

We have that for flu. We also have flu vaccines which are actually a cocktail of vaccines against a variety of different variants of flu. These are modified and updated depending on any changes each year and most of the changes are relatively small.

The Spanish, Hong Kong and other major flu outbreaks were significantly different from endemic flu. Sometimes they arose from animals again e.g. swine flu, bird flu. These are so different we refer to them as different strains , whereas the changes in covid19 are still relatively small so we call them different variants.

Out of interest, The world has been preparing for a completely novel flu strain (the next Spanish flu) and an ensuing pandemic for years. Our entire flu pandemic plans were based on flu.

And thus fatally flawed.

Because flu is transmitted in the vast majority of cases when someone is symptomatic. British response to “suppress” didn’t stand a chance in the first few months because covid is transmitted in the asymptomatic phase just as much.

Yes, it will keeper going forever, as long as it had a reservoir, like children and teens.

I have no idea what our exit strategy is. I don't think the world has one yet. It needs to be Global.

@lljkk

I sort of thought cytokine storm often caused by breakdown of lung lining (not covid virus directly) was a big reason for high C19 death toll. That's why steroids are recommended & may help (severe cases only). So like flu, it's secondary complications not the actual virus that causes most harm.

I'm more allied with lockdown skeptics, actually, Marsha, sorry to disappoint you. So not one to support very strict controls. I may be wrong. The high costs of controlling the virus & harms to young people dismay me. I'm grateful UK govts have tried hard to keep F2F learning going most of the last 16m, at least ... many countries gave up on young people. :( We've living in a giant experiment because never in history was there shutdowns of society like happened since early 2020. You can all hope my concerns about the harms from Lockdowns themselves are hugely disproportionate & misplaced. Maybe I'm thinking too long term.

No not disappointing at all. I agree with you in some ways. It was more the pp who said if only Western countries had acted straight away - I’m wondering if it’s even possible to contain and eliminate something like Covid on a worldwide scale if you do this. I think it might not be possible, but I’m not certain.

“New Zealand style max suppression.”

If we’d all acted like China (or New Zealand) in February 2020, we could potentially have avoided all this.

But the genie is out of the bottle now.

@roguetomato

As I understand, as long as the virus is circulating and spreading freely, they will keep mutating. That is why we need to get as many people vaccinated to reduce the number of susceptible people. Once we passed the threshold of % needed for herd immunity is established, the virus will slow down and it will be the end of pandemic.

Nope - THAT will end the epidemic of that particular variant.

The % requirement for herd immunity is quite complex, but effectively you have the following factors:

• % vaccinated
• % suppression of transmission due to vaccine (i.e. how likely it is a vaccinated person will catch and pass on the virus compared to a non-vaccinated person)
• R0 for the strain - the more infectious the strain, the higher the threshold for herd immunity.

Suppressing transmission is one of the first things to give when vaccines start to fail (as Van Tam explained a couple of weeks back).

Given sufficient vaccine "escape" capability and sufficient infectiousness, it's quite possible that herd immunity will not be possible.

Yes Marsha. I said potentially because every country in the world would have had to lockdown in concert to have stood a chance of completely suppressing the virus.

And there’s nothing to say it wouldn’t have survived in reservoirs (e.g. mink) and then just come back.

everythingthelighttouches and lljkk thank you for your hugely informative replies!

@everythingthelighttouches

Yes Marsha. I said potentially because every country in the world would have had to lockdown in concert to have stood a chance of completely suppressing the virus.

And there’s nothing to say it wouldn’t have survived in reservoirs (e.g. mink) and then just come back.

True re minks.

Maybe we’ll see a faster response to next one, although it’s hard to imagine every country doing it, maybe we could

Yes it can mutate forever.

But that doesn’t mean it necessarily has infinite room to continue getting more transmissible. Think of evolution like a genetic search for the fittest virus. At some point, the virus will approach the optimum structure to spread. It won’t just continue getting more effective forever.

It will continue to evolve to escape current immunity, but mRNA vaccines can be manufactured quickly, at scale, and with updated genetic payloads to compensate for the latest variants.

We’ll be back to normal soon enough, with a booster shot every year or so for a while.

Oh, and zero covid was never a workable strategy long term. Never. This thing was always getting out. Even with China style suppression. It’s too infectious.

@everythingthelighttouches

Yes Marsha. I said potentially because every country in the world would have had to lockdown in concert to have stood a chance of completely suppressing the virus.

And there’s nothing to say it wouldn’t have survived in reservoirs (e.g. mink) and then just come back.

The world couldn't have suppressed the virus.. but individual nations within it could have, and indeed have done!.

@strangeshapedpotato, thank you for explanation!

@everythingthelighttouches

“New Zealand style max suppression.”

If we’d all acted like China (or New Zealand) in February 2020, we could potentially have avoided all this.

But the genie is out of the bottle now.

We were at a few hundred cases and single figure deaths recently.

An adequate test trace and isolate system could make mincemeat of that.