Abrocitinib Treatment of Atopic Dermatitis in Children 2 to Less Than 6 Years of Age

This clinical study is designed to test how well a medicine called abrocitinib works and how safe it is for young children (ages 2 to under 6) who have moderate-to-severe eczema (also known as atopic dermatitis).Eczema is a skin condition that can cause the skin to be dry, itchy, have scaly patches, blisters and skin infections. How the study works: * Children will be randomly placed into two groups: * 2 out of 3 will get the real medicine (abrocitinib). * 1 out of 3 will get a placebo (a look-alike liquid with no active medicine). * Neither the families nor the doctors will know which group each child is in (this is called double-blind). This study is seeking for children: * between 2 and under 6 years old. * Who have had eczema for at least 1 year. * Who have moderate-to-severe eczema at the start of the study, based on skin area affected and symptom scores. The medicine is given once a day as a liquid. The amount given depends on the child's body weight. If the child's eczema doesn't improve enough between weeks 4 and 8, the dose might be increased (still without anyone knowing which group they're in), unless the child can't tolerate it. All children will also use standard medicated creams during the study. The study will be up to 24 weeks long and there will be a screening period (up to 28 days) to make sure each child qualifies for the study.