Somewhere in between the last two posts on the spike protein.
This particular Coronavirus appears be mutating primarily by random single nucleotide substitutions resulting in copying errors, common for RNA viruses. Essentially one amino acid at a time. Sometimes multiple changes net a different phenotype— stronger binding or whatnot.
(My understanding is that The original change giving rise to this particular Coronovirus was a recombination of two different viruses from two different hosts). Happens in coronovirus but…
Really happens in influenza. Influenza is known for recombination. Top that off with regular mutations and you get a range of antigen profiles every season. Hence the need to vaccinate every year and given the old school vaccine technology, the need to predict the likely antigen sequences needed to confer immunity for the coming season.
I hope and think that covid will have a harder time getting really different but not impossible. We may need boosters because of both non long lasting immune response AND some antigenic drift.
As someone that has observed microbial evolution in real time, the math that bothers me is just the huge number of infections. Everytime the virus replicates there is tiny tiny chance for a “bad” mutation (avoids antibodies, worse outcomes). But by having millions infected at the same time AND possibly the selective pressure of natural and vaccine acquired antibodies we are running a very interesting evolutionary experiment.
Remember the selection just acts on reproductive success. Illness is only linked as far as it’s helps the virus reproduce in the body and/or spreads to new hosts.
And finally my little evolution spiel- natural variation happens, then some do better than others. Evolution directs nothing, it’s just a scorecard of reproductive success.
The fun part of microbial evolution is that it happens on an observable timescale and it’s possible to manipulate the conditions towards a desired outcome. Of course if we are stupid with the virus we unwittingly can rig the system towards bad outcomes for *home sapiens”.
My understanding is that we are inserting the mRNA code for the protein, cells build the antigenic protein, then create the immune response. Beyond that is getting out of my league.
The line of tweets talks about how a single protein was changed in the receptor region. Like he says, that could completely change the shape of the protein. However, I don’t think that’s particularly likely as it has to retain its basic ACE2 interaction. Emphasis on think there, that’s way beyond what I know.
I will say that I’m not particularly worried. I don’t think the vaccine is particularly likely to go from 95% effectiveness to 25% or whatever without genetic shift (this is drift, or smaller changes).
In addition to my admittedly weak hypothesis above, there’s another reassuring factor: the lack of reinfections. If this suddenly changed what we think is the main antigenic source of the virus, I’d guess that we’d see reinfections. That remains exceedingly rare thankfully.
You mean like vaccinating 5-30% of the population and continuing to let it rip, giving it millions and millions of chances to find a mutation around the vaccine?
I don’t know specifically how they picked the sequence. It might be rationally designed towards a specific domain of the protein. Or it could be that a range of sequences were tested for immune response and the strongest binding/antibody response was selected.
I would not be surprised if both approaches— the strongest response to a protein region that is considered less likely to mutate.
I’ve heard Pfizer v Moderna described as not identical sequences but essentially the same as far as antigenic properties. Moderna just has some extra stabilization that avoids the -80c requirement.
Hopefully the mRNA technology makes it easy and fast to keep up with the viral evolution.
I hope (but have no clue) that it can have a big impact on the flu vaccine technology as well.
In this case the key really has two parts (s1 subunit and s2 subunit). The s1 is what initially attaches, but the s2 is also useful to fuse the virus to the cell. The Pfizer vaccine, I think causes antibodies to against the s1.
Edit: There are also multiple parts of the s1 that the vaccine could target, and the Pfizer vaccine targets the “best” part. Although targeting any part should work at least somewhat.
Also Nate silver is taking some heat about his take about vaccine distribution. He’s right IMO, the elderly should be prioritized ahead of people with medical problems. By a lot. I think you could make a case for them being prioritized above medical workers tbh
I don’t even understand the argument from the other side. All I see is people being mad at Nate and telling him to stay in his lane. Ok, I get that. But what’s the actual reason why we’re prioritizing pre-existing conditions when age is a WAY more important factor in poor outcomes?
You could argue that it’s easier for someone who’s 70+ and retired to isolate and protect themselves than it is for a lot of people who are working-age with health risks.
I’d probably do people in assisted living first, which they are, then people with health risks who are 70+, then people with health risks who are working age, then people who are 70+.
But I’d put essential workers ahead of all of them - grocery store employees, people in meat packing plants, etc. We fucked them over BIG TIME as a country in this and this is the absolute least we can do to show them the slightest shred of human decency.
Eh, seems like fancy play syndrome to me. I’d just sort by age with the exception of healthcare providers.
I’m biased here though because my mom is 64 and I’m going to be worried and mad if she has to wait months longer than someone my age with a pre-existing condition despite my mom being like 5 times more likely to die.
Regarding the UK strain. I would take the UK governments statements with a handful of salt. Borris has just cancelled christmas at the last minute after saying he wouldnt. They are using “everything has changed because of this new variant” as the justification for that change.
Not saying its an outright lie. But if i had to guess, i would say they are amplifying and simplifying something that is probably not that clear cut.
Question: How do you know Borris is lying?
Answer: His lips are moving.
That study seems to identify 17 mutations or deletions which led to the emergence of this new UK variant, 8 of which are to do with the spike protein. UK’s Chief Scientific Adviser said the new variant contained 23 changes. Not sure why the difference. Only reference I could find for that specific number was from this November study on covid in mink
Yeah you gotta take a second test after 3 days in quarantine after landing even if you take a test 72 hours before departing for the city. Otherwise it’s 14 days quarantine.
Don’t see how anybody can effectively enforce it. What if you just don’t answer the door? They can’t force their way in. Plus, you can just lie to them when they ask. You’re not under oath.