I'll pass on flu shots. One of the problems is that they have to cook up the vaccine months and months in advance of the flu season, without having any idea of the genetic makeup of the eventual target virus. Not unlike predicting the weather for a given day -- six or eight months in advance.
I still remember the flu shots that were supposed to protect people from the swine flu, back in 1976. People were literally dropping dead before they could even get out of the building. Some became paralyzed.
There was not one single case of swine flu in the States.