I will preface this saying that I have some connections to the Moderna vaccine.

You can take all the vitamins that you like. Being "exposed" really is meaningless term. Unless you've been tested for antibodies, you never got it.

This thing does terrible things to your lungs. I have friends who I have run relays with who, months later, cannot walk up stairs without gasping for air. Their lungs look like a mess with scar tissue.
If you're a smoker, you're playing some serious Russian roulette by not getting the vaccine.

The 2nd shot will generally have a greater reaction because it is a much stronger dose. The Moderna addendum to their filing indicates that there is initial data that their vaccine actually prevents infection.
If the data is accurate, it would mean that you're not spreading it. You can't shed a virus that you're not infected with. I haven't seen the same data from Pfizer but I would be surprised if the results are not similar. Until there is definite evidence that you cannot asymptomatically shed the virus after vaccination, masks are still being recommended, in the interest of safety.