I hope that in the Covid Pandemic post-mortum, we discover if our masks OR the seasonal flue vaccine was the more protective against it - maybe even to what extent. It would be a shame to waste this miserable year of 2020 and not learn as much as we can. I've never had the flu and I always take the shot. I've never worn a mask until this year. Still, if wearing a mask routinely could help prevent seasonal flu, it might well be worth it going forward - at least in certain settings.
I used to chuckle (just a bit) when I flew and noticed folks, especially from Asia, wearing masks. Now, I'm not sure I'll ever fly again without a mask. Funny how you can teach an old fart (er, dog) a new trick once in a while.
YMMV