I would urge everyone to take vitamin D supplements during the late fall, winter and spring months. Vitamin D helps boost your immune system. Since we make less vitamin D in winter because we get less sun and absorb less sunlight in our skin then to synthesize vitamin D, make sure to take extra to keep your immune systems boosted.
I’d recommend other things but this will help your body all on its own.
I saw something on the HIH website about latitudes and adequate sunlight for making vitamin D.
IIRC, north of Boston there is inadequate sunlight from November through February for the making of any vitamin D. South of somewhere in South Carolina there is always adequate sunlight.