Vaccines is better or Vitamin C is better?

During the time I work in home care sector, I learned that the vaccine is actually a type of virus that is injected into the body and allow the body get used to it which is why I never take annual Flu shot in the past 10 years. Now I feel my body is much healthier than before. I don’t have allergy and cold whenever I feel having cold, simply take some vitamins C 1-3 days, 1000mg per day.
As Coronavirus become pandemic globally , do you think annual Flu shot still necessary?