You aren't answering my question...mRNA lasts much shorter than viral vector. As the paper I posted explains, viral vector is much more stable and has a lot more CD8+ killer T. About 10 times as much. And that was with 1 dose compared to 2 doses of mRNA. So in terms of cost, you are looking at 10 bucks compared to 40 to 60 bucks for Pfizer or Moderna repectively.
mRNA might sound fancy and all that, but in terms of effectiveness and cost it cannot compete with viral vector. Which is one reason it was never used until last year.
If you check out case fatality rate between UK and Germany, it's not surprising UK case fatality rate is a fraction that of Germany. AstraZeneca is the factor.
Statistically significant differences in T-cell count does not translate into clinically meaningful differences in vaccine effectiveness against hospitalization and death. Real world results matter more than laboratory measurements.
What is observed at the biological level does not necessarily translates into worse protection against hospitalization and death. Both mRNA and inactivated have very similar efficacy against hospitalization and death, regardless of the T-cell count levels observed at the biological level.