Never got ‘em for free!!! Tho, now in my dotage, w/Medicare they are “free.” I think Costco gives the shots for $10 for non-Medicare types. They used to cost @ $40, IIRC.
I’d rather avoid the flu if possible, and to that end, stay away from the public as much as possible. Probably more effective than any shot.
Get your Vit D3 levels checked...keep them between 50-70 and you likely will NOT get the flu...ever