IL7 and lymphopenia: Although not yet currently FDA approved, IL-7 has been used in over 620 adult and pediatric patients for a variety of reasons including, for example, to hasten bone marrow recovery after allogenic stem cell transplantation, to reverse lymphopenia due to HIV and idiopathic etiologies, to treat patients with various malignancies, to act as a vaccine adjuvant in dendritic cell vaccines in pediatric sarcoma, and in prostate cancer, to boost efficacy of checkpoint inhibitors in patients with urothelial cancer, and to treat various infectious disorders including sepsis and SARS-CoV-2 (9–17).