The late summer booster for AZ that will be issued (prob in the UK first) has already been adapted to this variant specifically and is in advanced trials.
The important thing to note is that the significance of this study goes beyond the AZ vaccine. Please correct me if I've missed one, but from what I've seen there aren't any other vaccines that have completed similar trials in South Africa. The "good news" about the other vaccines' effectiveness against the variant have been based on in vitro immune response[1], not real-world trials. What would be good to know though is what response the AZ vaccine had in tests similar to the ones performed with other vaccines.
The most recent news continues to reinforce the idea that AZ is simply not effective at ALL against the B.1.351 SA variant, which is worrisome if it ends up dominating outside of South Africa.
Pfizer and Moderna both seem to show lower neutralizing antibody responses, but not nothing, and while there is some question of if "2/3rds less is enough," there's also some other significant considerations around the T-cell response that's triggered by those two and its robust effectiveness even against B.1.351. But not so much with AZ, which continues to show itself as ineffective against the variant: https://www.medpagetoday.com/infectiousdisease/covid19/91658
The 2nd key reason is that no other vaccine is backed up by so much real world data as BT because of Israel. That is the very topic of this thread. That is why I thought it is self-explanatory.
Isn't that being a little optimistic? After all if this was good news, it wouldn't be news :-)
Fully appreciating the point: antibody response is not the only response of the immune system.
The other story on HN right now is "AstraZeneca vaccine doesn't prevent B1351 Covid in early trial" – a finding consistent with the results of this study (yes, yes, AZ vaccine != Pfizer/Moderna).
So what becomes interesting is: does the AZ vaccine not produce the same T-cell response as Pfizer/Moderna, or are these vaccines in fact broadly similar (mutants don't affect T-cells but affect antibodies). The latter wouldn't be consistent with Skelly 2021.
This paper is looking at a small scale human study in SA with mostly younger participants, which does make the results difficult to apply to the wider population.
They also only use a 4 week dosing schedule where the suggestion and actual rollout in the UK is following the 10-12 week schedule between first and second doses.
The variant in question seems to escape the majority of Antibody detection, but T-Cells still seem to provide significant protection against severe disease and death.
The main published results aren't yet from human scale studies but here is one in hamsters showing a comparison in organ damage and results between unvaccinated and vaccinated with the Oxford/AZ vaccine.
J&J uses a very rare human adenovirus, AZ uses a more common chimpanzee adenovirus. J&J also has the so-called 2PP modification on the Spike protein compared with the AZ vaccine. Good writeup here: https://berthub.eu/articles/posts/genetic-code-of-covid-19-v...
I've posted this before regarding the SA paper on AZ, worth taking a look at the below.
The probable outcome is minor to moderate symptoms that would normally be blocked by antibodies can still present (So no reduced transmission) but severe symptoms are still prevented by the vaccinated patients T-cells response.
This paper is looking at a small scale human study in SA with mostly younger participants, which does make the results difficult to apply to the wider population.
They also only use a 4 week dosing schedule where the suggestion and actual rollout in the UK is following the 10-12 week schedule between first and second doses which was shown to increase efficacy from ~70 to ~80% after the second dose (UK - Kent variant)
The variant in question seems to escape the majority of Antibody detection, but T-Cells still seem to provide significant protection against severe disease and death.
The main published results aren't yet from human scale studies but here is one in hamsters showing a comparison in organ damage and results between unvaccinated and vaccinated with the Oxford/AZ vaccine.
It's true that AZ isn't enough for herd immunity, but as I understand it neither is Pfizer or Moderna. It's also worth noting that AZ is extremely effective at preventing serious illness or death from the Delta variant (as are the other vaccines). Had we all gotten AZ months ago, we would be talking about the transmission of a virus that's been rendered much less menacing, which is a totally different risk-benefit calculus.
Yes, Astra-Zeneca has been shown to be repeatedly poor against variants, a big story in the UK right now is whether the increase in cases and sense of being behind the US is due to gov't overly committing to a shoddy vaccine, or if it's variants burning through unvaccinated populations.
The picture isn't nearly as rosey as OP makes it sound, unfortunately: sort of a gish gallop about knowing the rate at which we can expect buffer overflows in C, but in reply to a comment noting we don't have an ETA for ending security vulnerabilities, so they unintentionally implied the picture is good.
AstraZeneca is only 67% effective at preventing someone from contracting the delta variant, which isn't enough to prevent it from spreading without restrictions even at a 100% vaccination rate. I'm currently on the government website trying to book an AstraZeneca appointment in, but let's acknowledge that we're all going to need booster shots of Moderna or Pfizer after this.
The J&J and AZ vaccines both use a similar viral vector with a modified gene.
They target the same protein but just like with the mRNA vaccine they usually do not encode the entire protein but rather target specific amino acid chains in various regions of interest on the protein itself.
Other differences in the vaccine would be the level and type of immune response generated in general which will be based on the specific viral vector used, dose and regiment, adjuvants etc.
The study which measured the J&J efficacy also used a different methodology to this one.
Overall this is a very limited study and should be taken in context.
Another key part is that the T-cell response for the AZ vaccine group seems to remain intact.
>Although the correlation between antibody response and vaccine efficacy is high, which suggests that the neutralizing antibody response is important, T-cell responses may contribute to protection from Covid-19 even in the presence of lower neutralizing antibody titers.32 In a post hoc analysis reported here, we found that in spike-specific T cells that expanded after vaccination with ChAdOx1 nCoV-19, the majority of antigens and epitopes remained intact in recognition of the B.1.351 variant.
Until we have data on actual severe cases it seems that the AZ vaccine is still effective at preventing hospitalization and deaths. There were also no tracking of non-symptomatic cases in the study so the actual prevalence of infections in either group is unkown.
https://www.cnbc.com/2021/02/05/astrazeneca-covid-vaccine-wo...
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