[cctop]

One other thing about the vaccine trial is that the trial screened for asymptomatic infections, not just symptomatic infections as the Moderna and Pfizer/BioNTech trials did, so the comparisons are a bit apples-to-oranges:

https://www.ox.ac.uk/news/2020-11-23-oxf...19-vaccine

Per that link, 70% efficacy for the Oxford/AZ vaccine is an average of it being 90% effective giving a half-dose first and 62% effective giving a full dose first.

Somewhere there's an AstraZenaca marketing exec pulling out his hair that the headlines say 70% effective rather than 90% effective if administered in a certain way.

I was curious why a first half-dose would be more effective than a full dose, so I found this article:

https://www.nature.com/articles/d41586-020-03326-w

The theories are:
1)  small sample size.  With a larger sample size the actual number might be as low as 66%.
2)  a half first dose does a better job stimulating production of the "memory" T-cells.  It's possible that more time between a full first dose and second dose would do the same thing.
3)  the Oxford/AZ vaccine is based on a modified chimpanzee virus.  A full dose might be prompting the immune system to fight the chimp virus as well.

[cctop]

One other thing about the vaccine trial is that the trial screened for asymptomatic infections, not just symptomatic infections as the Moderna and Pfizer/BioNTech trials did, so the comparisons are a bit apples-to-oranges:

https://www.ox.ac.uk/news/2020-11-23-oxf...19-vaccine

Per that link, 70% efficacy for the Oxford/AZ vaccine is an average of it being 90% effective giving a half-dose first and 62% effective giving a full dose first.

Somewhere there's an AstraZenaca marketing exec pulling out his hair that the headlines say 70% effective rather than 90% effective if administered in a certain way.

I was curious why a first half-dose would be more effective than a full dose, so I found this article:

https://www.nature.com/articles/d41586-020-03326-w

The theories are:
1)  small sample size.  With a larger sample size the actual number might be as low as 66%.
2)  a half first dose does a better job stimulating production of the "memory" T-cells.  It's possible that more time between a full first dose and second dose would do the same thing.
3)  the Oxford/AZ vaccine is based on a modified chimpanzee virus.  A full dose might be prompting the immune system to fight the chimp virus as well.