Read on Twitter
1/n
Today, I read a #COVID19 #Vaccine piece repeating that the Oxford team were 80% confident that there vaccine would work. This had previously struck me as an odd figure, and not hearing any justifciation for this level of confidence, I decided to sift the evidence.
Today, I read a #COVID19 #Vaccine piece repeating that the Oxford team were 80% confident that there vaccine would work. This had previously struck me as an odd figure, and not hearing any justifciation for this level of confidence, I decided to sift the evidence.
2/n
I thought a good place to start was to delve into the only paper I was aware of that reported on the performance of the #chadox1 vaccine platform in humans. Here's that paper: https://www.nejm.org/doi/full/10.1056/NEJMoa1411627
I thought a good place to start was to delve into the only paper I was aware of that reported on the performance of the #chadox1 vaccine platform in humans. Here's that paper: https://www.nejm.org/doi/full/10.1056/NEJMoa1411627
3/n
This paper compares immunological correlates that we think might be linked to protective immunity - i.e. those immune parameters that might protect against an acute virus infection.
This paper compares immunological correlates that we think might be linked to protective immunity - i.e. those immune parameters that might protect against an acute virus infection.
4/n
We know that the #VSV_EBOV vaccine worked really well during vaccination campaigns to protect against #Ebolavirus infection. The paper above looked at the levels of antibodies in human sera following #VSV_EBOV vaccination compared to samples from a phase 1 trial of #chadox1
We know that the #VSV_EBOV vaccine worked really well during vaccination campaigns to protect against #Ebolavirus infection. The paper above looked at the levels of antibodies in human sera following #VSV_EBOV vaccination compared to samples from a phase 1 trial of #chadox1
5/n
First thing to note. The #ChadOx1 data is following a boost (second immunisation) with a different vaccine platform ( #MVA); this isnt yet included in the #Covid_19 trial (as far as I am aware). This boost has been shown to be critical to get decent antibody levels.
First thing to note. The #ChadOx1 data is following a boost (second immunisation) with a different vaccine platform ( #MVA); this isnt yet included in the #Covid_19 trial (as far as I am aware). This boost has been shown to be critical to get decent antibody levels.
6/n
But putting that aside, the data in the paper does, I think, give insight into where the Oxford confidence is coming from.
But putting that aside, the data in the paper does, I think, give insight into where the Oxford confidence is coming from.
The levels of antibody for the boosted #ChAd3_EBOV and non-boosted #VSV_EBOV were 752 and 921, respectively. That means that the ChAd3 vaccine levels were 81% of those seen in the protective VSV vaccine. Pretty much near the confidence levels Oxford have in their COVID19 vaccine
8/n
If you look at the #neutralising_antibody levels (those viruses known to directly block infetion by the virus) and a very important part of the protection given then the #ChAd3 levels were 14.9 compared to 22.2 for the VSV. That's 67%. Maybe Oxford should be 67% confident?
If you look at the #neutralising_antibody levels (those viruses known to directly block infetion by the virus) and a very important part of the protection given then the #ChAd3 levels were 14.9 compared to 22.2 for the VSV. That's 67%. Maybe Oxford should be 67% confident?
9/9
I might be barking up the wrong tree, and they might have other compelling data. It's worth pursuing that's for sure but putting confidence levels on these things might be a tad misplaced? Finally, ChAdOx1 and ChAd3 arent the same vector, but I'd expect they'd perform similar
I might be barking up the wrong tree, and they might have other compelling data. It's worth pursuing that's for sure but putting confidence levels on these things might be a tad misplaced? Finally, ChAdOx1 and ChAd3 arent the same vector, but I'd expect they'd perform similar
10/9
**CORRECTION**
Point 8 above "...those viruses known to directly block infetion by the virus..." should say 'those ANTIBODIES known to block..."
Doh!
**CORRECTION**
Point 8 above "...those viruses known to directly block infetion by the virus..." should say 'those ANTIBODIES known to block..."
Doh!
11/9
And of course in point 1 I meant to use the homophone 'their' not 'there'.
I dont have time to proof -read twitter 'till after the event :)
And of course in point 1 I meant to use the homophone 'their' not 'there'.
I dont have time to proof -read twitter 'till after the event :)
