The annual flu shot has a 30% failure rate. Not myth, science.
The founding fathers didn't have to contend with a constant influx of active influenza pathogens from the source of 8 in 10 flu strains: southeastern China, where people, pigs and birds live in close proximity, and the bugs jump the barrier with impunity, evolve rapidly, and move with travelers. Sunshine has nothing to do with influenza virulence and suseptability. THey did, however, suffer from a smallpox epidemic during the Revolution. Prefer that?