The phrase "is prevalent" refers to something that is widespread, common or dominant in a particular area or situation. The antonyms for "is prevalent" can be words like rare, uncommon, infrequent, unusual, scarce or sparse. These words refer to something that is not common or widespread in a particular setting, and suggests that the thing or situation being described is something unique, exceptional or rare. For instance, a rare disease is less common than a prevalent one, and an infrequent behavior is less dominant or widespread than a prevalent one. Using these antonyms of "is prevalent" can add depth and nuance to your descriptions, as well as greater precision in your communication.