This study is broken up into 6 periods: 1) The screening period 2) Initial study drug period 3) Maintenance study drug period 4) Open-label period 5) End of study 6) Safety follow-up If your child joins this study, they will have a screening period that will last up to 30 days and involve at least 2 in-person clinic visits. During the screening period, your child will have the following tests and procedures:

• Physical exam
• Blood work
• Skin swab
• Vital signs

If your child is eligible to join, they will get a random assignment (like the flip of a coin) to receive either the study drug or placebo (an inactive substance). The study doctor will stop any eczema treatments your child is using 7 days before the initial study drug period. Your child will have up to 17 visits to our clinic during the study. During the initial treatment period, you child will receive the study drug or placebo every 2 weeks for the first 4 weeks of the study. After the first 4 weeks, they will receive the study drug or placebo every 4 weeks through week 24. After 24 weeks, the maintenance period will begin. If your child wants to remain in the study and has not started any new treatment, they will get a random assignment assigned to receive the study drug at a dose of 150mg or 300 mg every 4 or 8 weeks for the next 28 weeks. The open-label period begins after the maintenance period is finished. If your child chooses to continue during this period, they will get the study drug at a dose of 300 mg every 4 weeks for 28 weeks. The study will end after the open-label period is complete and then move in to the safety follow-up period. In the safety follow-up period, your child will have a visit with the study doctor 16 weeks after the study ends to see how they are doing.