 This study found that the number of infants hospitalized due to COVID-19 increased significantly in 2021 compared to 2020, when the virus was still primarily caused by the wild strain. Additionally, the presence of comorbidities such as premature birth or cardiac issues was linked to a more severe course of illness. This article was authored by Malgorzata Polowska, Maria Polkorska-Spiewak, Ava Talorek, and others.