There is one derivative of vitamin A that has proven to be extremely effective with acne, and that is Isotretinoin (commonly known as Accutane). However, Accutane is only available as an oral medication, and the same effects are not nearly as strong when vitamin A is used topically.
Topical products with vitamin A belong to a family of compounds called, “retinoids”. There are many different types of retinoids. Some of them—those that contain retinoic acid—have been shown to reduce both blackheads and whiteheads but do not have significant effects on inflamed acne pimples. Other types of retinoids, including retinol or “vitamin A” serums, have not been proven to have beneficial effects on acne. Thus, if you are looking to improve your acne, I would stick with proven anti-acne ingredients such as benzoyl peroxide, salicylic acid, glycolic acid etc.