So 2 people in the house have the flu and I haven’t gotten it so far but I was wondering how to keep it that way. I have been taking vitamins every day since, but as far as I know it doesn’t actually prevent?.

There’s nothing you can do that guarantees you won’t get it if you share living spaces. Drink enough, make sure you’re rested is the best thing you can do. Maybe minimise contact.

Best way to prevent it is to avoid contact as much as possible (obviously don't share food, drinks etc) wash your hands frequently and sanitize common surfaces (like door handles, bathroom faucets and similar.) Get proper sleep so your immune system is in good shape. To some extent though there's only so much you can do.

Take immune boosters! I use Emergen-C immune+ during sick season and whenever people around me are sick.

^ it won’t necessarily prevent you from getting sick, but can help lessen the symptoms if you do end up sick.

Vitamin C has anecdotal evidence, but zinc has been proven in studies to reduce severity/boost immunity. I take it as soon as I get a sore throat or other warning symptoms. It only works within the first 24 hours of symptoms, so take as soon as you feel something

Correction: I don’t think it boosts immunity, but rather limits/reduces virus replication