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Covid booster: different or same vaccines?

The home for all non-political Coronavirus (Covid-19) discussions on The Lemon Fool
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This is the home for all non-political Coronavirus (Covid-19) discussions on The Lemon Fool
9873210
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Re: Covid booster: different or same vaccines?

#452309

Postby 9873210 » October 22nd, 2021, 4:37 pm

pje16 wrote:Does anyone know the answer?

If the question is "Does anybody know if it is better to get heterogeneous or homogeneous boosters?" the answer is "no, nobody knows." This is why different experts come to different conclusions.

"The evidence suggests" is a long way from a definitive "know". Unfortunately many people are unhappy making decision in the face of uncertainty. Even more unfortunately this sometimes feeds back to decision makers, locking in decisions even if later evidence suggests strongly that a change of course would be better.

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Re: Covid booster: different or same vaccines?

#452312

Postby pje16 » October 22nd, 2021, 4:42 pm

oh pardon me !!!!!!!!!!!!!!!! :roll:

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Re: Covid booster: different or same vaccines?

#452314

Postby 9873210 » October 22nd, 2021, 4:44 pm

pje16 wrote:
Hallucigenia wrote:They don't work in a totally different way. They use different delivery methods, but they both deliver instructions to the body to make a fragment of virus protein, which trains up the body's immune defences. But it's like getting the same letter sent by post and by Fedex.

They do AFAIK
https://www.healthline.com/health/astra ... -they-work
The Pfizer-BioNTech vaccine uses mRNA technology, while the AstraZeneca vaccine uses an adenovirus vector.
quite prepared to be corrected
Your link doesn't work so I can't see what it says

In the healthline article you could swap (and renumber) steps 3-5 for AstraZeneca and steps 5-7 for Pfizer-BioNTech and it would still be entirely accurate.

If you view the job of the vaccine is to get the body to display the spike protein (or other antigen) they are different.
If you view the job of the vaccine is to develop immunity most of the heavy lifting is done by the immune system after the spike protein is displayed and they have a lot in common.

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Re: Covid booster: different or same vaccines?

#452499

Postby Hallucigenia » October 23rd, 2021, 1:56 pm

pje16 wrote:The Pfizer-BioNTech vaccine uses mRNA technology, while the AstraZeneca vaccine uses an adenovirus vector.


That's correct - but they are two technologies for delivering a message to the protein-making machinery, which then makes a bit of virus protein which the immune system recognises. They use different delivery systems (hence the post v Fedex analogy) but from an immunological point of view, they're essentially working the same way.

Whereas injecting premade protein, or inactivated virus, would be considered "working in a totally different way".

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Re: Covid booster: different or same vaccines?

#452521

Postby Julian » October 23rd, 2021, 6:06 pm

Hallucigenia wrote:
pje16 wrote:The Pfizer-BioNTech vaccine uses mRNA technology, while the AstraZeneca vaccine uses an adenovirus vector.


That's correct - but they are two technologies for delivering a message to the protein-making machinery, which then makes a bit of virus protein which the immune system recognises. They use different delivery systems (hence the post v Fedex analogy) but from an immunological point of view, they're essentially working the same way.

Whereas injecting premade protein, or inactivated virus, would be considered "working in a totally different way".

Might there not be some potentially significant differences though that might be applicable re booster shot strategy, in particular any difference in immune response to the adenoviral vector of the AZ (or J&J) vaccine vs to the lipid nanoparticles that I believe are used by both Moderna and Pfizer for their vaccines? As I understand it a chimp adenovirus was chosen by the Oxford team specifically to minimise the chance of the host's immune system mugging the delivery driver before he/she delivers the message (and I believe that Sputnik V uses two different human adenoviral vectors for its first and second doses for the same reason).

I haven't really seen any interim efficacy data from the Southampton Cov-boost study which as I understand it is an ongoing study looking at all sorts of combinations of homogeneous primary vaccination plus different boosters. I do wonder how AZ+AZ + AZ-boost compared with AZ+AZ + Pfizer-or-Moderna-boost in terms of efficacy either in interim Southampton Cov-boost data or from any other study that might have looked at those specific scenarios. If there was any significant deficit for the all-AZ case might it at least be a possibility that immunity to the viral vector was becoming an issue? Or is it the case that the human immune response to all of these adenoviruses chosen as vectors, maybe in particular the Oxford not-even-human one, is so poor and/or poorly maintained that it would take an awful lot of repeat dosing before any troubling level of immunity to the viral vector itself is likely to become an issue?

It's probably another appropriate time to mention that I am most definitely not an expert and as a computer scientist I am sure that my understanding of the basic concepts underlying such discussions is woefully shallow and incomplete compared to that of someone who has dedicated years of their tertiary education time and decades of their subsequent career to studying this stuff so my understanding leading me to the speculation above might be totally wrong. If so then polite corrections to any flawed understanding on my part are always welcomed.

- Julian


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