This years shot is supposed to give 63% immunity. Next years could be worse or better, they have to out guess the flu mutation. There has been a lot of progress in medical science in 50 years. They are now working on a vaccine that will innoculate for all types of flu which you will need to get only once in every 10 years.
havent gotten flu shots ever, and i hardly ever get the flu. maybe twice i the last 35 years.