This isn't the final evaluation. There will be another at ~150 cases. The numbers may seem small, but this is enough for the purpose of deciding for or against approval. Anything over 80% effectiveness would likely be approved, so it doesn't matter whether the true value (insofar one exists) is 90%, 95%, or something in between. It's useful regardless.
Oh, I didn't know that, thanks. I'm sure it's enough for statistical significance given the difference, I was just wondering why there were so few cases in 30k people, but it looks like that's just the normal case rate.
