4 ms·

The half dose being more effective than the full one is a potential red flag that the study results are off.

IgorPartola 6y ago
From what I read it’s a lot more complex than that. One theory is that it’s due to how the AZ vaccine is constructed. It is a neutered chimp adenovirus that cannot reproduce but is able to infect cells and cause them to produce the COVID spike protein that the immune system can detect and react to. So it is a two stage process: infect the cell, make it produce the spike protein, have the spike protein attach to another cell, and finally have the immune system respond to the spike protein. The idea is that if you inject too high a dose initially, the immune system will instead respond to the adenovirus and kill it before it can carry out its intended job here. Having a slower initial response will allow for enough COVID spike protein to be produced to develop an immunity to that. I am absolutely not an expert on this. Just paraphrasing something I read.
- Exmoor 6y ago
  That's accurate. It was a known concern going into the trials. Enough so that the Russian Sputnik V vaccine purposely used a different adenovirus in the first dose and the second dose and appears to have about 92% efficacy rate. I believe Oxford is also planning on running a trial using a mix of the Oxford and Spuknik vaccines to see if it improves efficacy.
ulfw 6y ago
The fact it was an error and they can't really explain why it's better, but have some ideas why it could be, is a red flag.
athriren 6y ago
the immune system is where intuition goes to die and it is not uncommon for lower potency vaccines to provoke more effective immune responses. i do agree oxford and astrazeneca have not handled this well. it seems quite clearly an error based on a volume of documentation but leadership at both institutions appear to be insisting it was not, which degrades trust at a time when many members of the public do not trust health officials to tell them which way is up.

From what I read it’s a lot more complex than that. One theory is that it’s due to how the AZ vaccine is constructed. It is a neutered chimp adenovirus that cannot reproduce but is able to infect cells and cause them to produce the COVID spike protein that the immune system can detect and react to. So it is a two stage process: infect the cell, make it produce the spike protein, have the spike protein attach to another cell, and finally have the immune system respond to the spike protein. The idea is that if you inject too high a dose initially, the immune system will instead respond to the adenovirus and kill it before it can carry out its intended job here. Having a slower initial response will allow for enough COVID spike protein to be produced to develop an immunity to that. I am absolutely not an expert on this. Just paraphrasing something I read.

Exmoor 6y ago
That's accurate. It was a known concern going into the trials. Enough so that the Russian Sputnik V vaccine purposely used a different adenovirus in the first dose and the second dose and appears to have about 92% efficacy rate. I believe Oxford is also planning on running a trial using a mix of the Oxford and Spuknik vaccines to see if it improves efficacy.

ulfw 6y ago

The fact it was an error and they can't really explain why it's better, but have some ideas why it could be, is a red flag.

athriren 6y ago

the immune system is where intuition goes to die and it is not uncommon for lower potency vaccines to provoke more effective immune responses. i do agree oxford and astrazeneca have not handled this well. it seems quite clearly an error based on a volume of documentation but leadership at both institutions appear to be insisting it was not, which degrades trust at a time when many members of the public do not trust health officials to tell them which way is up.