I don’t know if the game renders all this, but thre are more types of flu than just what the flu shot covers, the flu shot is just precise in what it defends against and usually has the be updated anually or even biannually because of the gentic simplicity of the virus.
Yes they are. Both in game and in real life.
I personally have taken flu shots with each of my survivor that did not die on the first day and none of them have ever contracted flu after that.
Yeah, the code for the flu shot gives you an effect that blocks the flu. Common cold and other illnesses are not affected.
It is 100% effective against the flu, though, so those crazy lab guys really do know what they’re doing sometimes, it would seem.