Can warforged become vampires? Send Tweet. #DnD
— The Quarantined Dungeon Master (@BigSquishyDM) February 14, 2020
Under 3.5 rules, warforged couldn't become vampires. Under 5E rules, they are humanoids and thus technically could. Personally I would say that they CANNOT become standard vampires, for reasons too long to go into in a tweet; I'd create a unique warforged expression of vampirism.
— Keith Baker (@HellcowKeith) February 14, 2020