Formal attire is slightly less formal than black-tie is acceptable. So, a tuxedo isn't required, but the event is still formal enough for one to be appropriate. The choices are the same as with black-tie: a floor-length gown, a fancy cocktail dress, or a dressy pantsuit.
In order to keep all of our friends and family as safe as possible, we are requiring that everyone attending be fully vaccinated per CDC guidlines and have at least one booster shot of the Covid-19 vaccine.