They also tested a lot more subjects for Covid and detected a lot of asymptomatic ones. Their success rate is probably nearer the other vaccines that didn't test asymptomatic subjects.
Can you share more about this? Where have Oxford/AZ shared their testing protocol? Indeed, I was surprised to learn that the Pfizer and Moderna trials did not test participants unless they showed symptoms. Meaning: we don’t know if their vaccines prevent transmission of the virus. It specifically was not the measuring stick for their definition of efficacy.
I believe Moderna is currently conducting a new trial to ascertain the transmission question. Until we know for sure, all the talk about herd immunity may be moot.