Flu vaccines are an interesting one. They're changed each year (in UK, Fluenz Tetra is used primarily) based on a guess at the 4 most likely prevalent strains for the forthcoming season. I don't see how you can hide behind "rigourously tested" "longitudinal scientific observations" and such.

All public vaccination schemes are for populations, but flu vaccination in this form seems much more of a gamble than tried-and-tested vaccines.

AIR one-in-ten getting the vaccine get "flu-like symptoms"; but it's for the population as a whole.