flu vaccine doesn’t even work on most strains of flu, I don’t see how it would help with this. My nurse wife could tell me exactly what percentage of strains it works on, but it’s in the neighborhood of 20. Neither of us has ever had one, I have missed one day of work in 18 years.
When the yearly vaccine is developed, it is always a crap shoot. The virologists, based on their science and experience, try to determine what unique antigens the new season’s virus will feature and then try to design a vaccine that will take aim at those antigens and stop the virus. Sometimes the new vaccine is not as effective as the scientists hoped . Clinically when that happens as in 2018-2019 people who received the vaccine still got sick but the observation was that they as a group were not as severely ill and did not have the same death rate as people who were not vaccinated. So most physicians continued to recommend its administration. There are of course people who are genetically endowed with the capability to resist influenza vaccine as there are people who have the inherent genes to resist COVID-19. There is still much to learn. IMHO you just might have a bit of cross immunity to COVID-19 if you received yearly flu vaccines for the past 15 years.
Once I discovered plant based Vitamin D and C, i don’t get sick anymore. EVER. Not even when everyone else is falling down sick all around me.