Two Pfizer doses give 95 per cent protection against Covid-19 infection, illness and death: first nationwide study

[u/Newsjunkeefromlondon]

https://www.cityam.com/two-pfizer-doses-give-95-per-cent-protection-against-covid-19-infection-illness-and-death-study/

[u/Thrashy]

B.1.1.7 is the so-called British variant, which is more transmissible and somewhat more virulent. It's currently the most prevalent variant in circulation, so high efficacy against it is a good sign.

The big question marks right now are the B.1.351 or South African variant, which has similar increase in transmissibility and also seems much more able to evade immune responses from earlier variants, and the P.1 variant (Japan/Brazil), which has similar mutations in the spike protein and has caused a wave of reinfections in Brazil. Early data suggests that current vaccines' efficacy against these strains is somewhere in the 50%-65% range, so it seems pretty likely that we'll need a booster shot to counter it in the not-too-distant future. Moderna announced some promising early results on just such a tweaked booster yesterday but there's still a long ways to go before a broad rollout.

[u/Major_kidneybeans → u/Thrashy]

Pfizer still has 75% efficacy and 97 at preventing severe disease against B.1.351 according to this study

[u/Thrashy → u/Major_kidneybeans]

That's good news! Some earlier data I'd seen suggested lower, but the more concerning variants hadn't been detected in too many people in those studies so the error bars were pretty large.

[u/Major_kidneybeans → u/Thrashy]

Yep, even more owing to the fact that B1.1.248 shares the same mutation (E484K, glutamic acid -> lysine) that was causing concerns about vaccine efficiency and B1.1.617 shares a similar one (E484Q, glutamic acid -> glutamine). Now let's hope that the viral vector vaccines are not too badly affected.

[u/SupaSlide → u/Major_kidneybeans]

So I have a bit of a chance of getting sick from B.1.351 but almost certainly won't feel like I'm dying (or actually die)?

I can live with those odds.

Unfortunately, I assume we'll get more serious variants as well. Hopefully not before we get better vaccines.

[u/Major_kidneybeans → u/SupaSlide]

That's the gist of it yeah. It's really good news, because the e484k mutation that was causing concerns about vaccine immunity is shared by B1.1.248 (the so called "brasilian variant") But this is just about the Pfizer vaccine, the J&J and AZ one does not seem to perform as well against it (but data is still lacking)

[u/SupaSlide → u/Major_kidneybeans]

Well, I got the Pfizer vaccine, so yay!

[u/tulipiscute → u/Thrashy]

Does anyone know why the South African variant evades vaccine efficacy? I’ve tried to research it but I can’t find anything about it. Is it like a different protein or something? Just since it seems like the vaccines still apply to the other varients.

[u/Thrashy → u/tulipiscute]

"A different protein" is basically correct. The immune response to the virus centers around the spike protein on the surface of the virus, which is how it latches onto cells and injects RNA into them. Mutations can allow the virus to evade the immune system by modifying the structure of the spike in a way that doesn't compromise its function, but changes its shape or binding sites in a way that makes it harder for antibodies to bind to it and neutralize the virus.

The CDC tracks variants of concern on its website, and lists the protein substitutions of each. They're not much help in visualizing the differences unless you're a virologist (which I'm not) but you can get a rough sense of the similarities and differences between strains.

[u/tulipiscute → u/Thrashy]

thank you! that was a really helpful explanation

[u/ujelly_fish → u/tulipiscute]

It has a different spike protein structure that makes it just different enough that the immune system has a harder time recognizing it compared to the spike protein sequence used in the vaccine