Flu Vaccine Studies: Pseudo-Randomized or Untrustworthy Results?

Flu Vaccine Studies: Pseudo-Randomized or Untrustworthy Results?: Clayton J. Baker: I often wondered why the effectiveness of the flu vaccine has been consistently mediocre, usually below 50%. The usual explanation is mismatching with the circulating strains, but is it possible that much of what is being estimated is a compilation of biases?