Is 30 % a Good Value for the Flue Vaccine?

30 % seems really low to me. That seems like, that almost seems like, is there much point? As someone who works in this field, and you were impressed by the numbers, how do you explain that then? Is it just because i've just thrown so much resource as ata i did, it just turn out this was an easier thing to make a vaxine for than we thought? Like, how can we explain that, after all these years of diseases and things that we just can't crack, that they are able to just smash it out of the park so quickly?