A group of people are presenting with a delayed onset of blisters?

A delayed onset of blisters in a group of people could suggest a common exposure to an irritant or allergen, such as a chemical or toxin, leading to delayed hypersensitivity reactions. Conditions like contact dermatitis or certain infections, such as herpes simplex, might also present this way. It's important to consider the exposure history and any shared activities or environments among the individuals. Prompt medical evaluation is recommended to determine the underlying cause and appropriate treatment.