It's interesting to layman's eyes that the dosing regime using 1.5 doses is more effective than the one using 2 doses as I would expect the inverse; are there any plausible explanations for this?
I think its possible that this is just noise. The difference between '60%' and '90%' might just be a handful of cases.
They show that it works though, thats the main thing.
edit: e.g. of those 130 cases lets assume half were in each regimen experiment. So 65 cases in the 'two full doses experiment' if they got 60% efficiacy then that means about 26 people with the vaccine got covid vs 39 with placebo. In the 'half dose then full dose' experiment if they got 90% efficacy then that means about 7 people with the vaccine got covid vs 58 with placebo. So the difference between 60% and 90% is 19 people. They show that the vaccine works but there is lots of uncertainty between the two dosing regimens.
Edit: why the downvotes?
This is I think why the mRNA vaccines are doing better. They don't use a virus as a vector, they use a less convoluted vector of a more basic mRNA instruction set. They're also in a way more "scalable" in that a future disease or a mutation of Covid with a new spike protein could have a new vaccine made quickly by tweaking the mRNA sequence.
Pfizer and Moderna vaccines are not vectored.