I don't want people to come at me but ours is 6 months, hasn't vaccinated at all yet and hasn't got sick even once. Even during cold/flu season when my entire family got sick. (He was born in January) My brother's kids get sick constantlyyy and they're all vaccinated. 🤷‍♀️ Idk, makes me wonder! He's also exclusively breastfed til now which plays a large role.