Vodka doesn't really add its own very perceptible flavor, rather it acts as a behind the scenes flavor booster for the varying ingredients: the savory sweetness of the tomatoes, richness of the cream, and heat of the peppers. If you don't consume vodka you can omit it in this spicy rigatoni recipe. While it won't taste exactly the same, you'll still have an enjoyably spicy and creamy tomato sauce.