The real-world effectiveness of preschoolers wearing masks on campus to prevent respiratory infectious diseases: a cohort study.

Background: Respiratory infections are common in the pediatric population. Preschoolers, especially those in kindergarten and 3-6 years old, are highly vulnerable to various respiratory infections.

Objective: To investigate the efficacy of indoor mask-wearing in mitigating respiratory infections in preschoolers in a real-world campus setting.