Hi gwr,
You are correct.
Have never taken a flu vaccine shot in my life.
However, when I was younger, had many "shots" to try and overcome the symptoms.
Sometime they worked, and I got cured in about fourteen days.
Sometimes they didn't and it took me two weeks to get cured.
Today, I just purchase another few boxes of tissues (and the occasional "shot" seems to help as well).
Good Luck to all!