i get a flu shot every season.
i have done this, for 20 years now.
can't remember the last time i actually got the flu.
bad head colds, yes, other viruses, yes, but not the flu.
i get the flu shot in october.
i don't know why you would want to wait any later than that.
3 flu viruses were included in the shot.
the best they can do, is track and monitor and try to create a flu shot that covers the worse offenders, they can't get them all.
and flu viruses are pretty varied.