A Study of Baricitinib (LY3009104) in Children With COVID-19

Inclusion Criteria: * Hospitalized with coronavirus (SARS-CoV-2) infection. * Male or female participants from 1 to \<18 years of age. * Requires supplemental oxygen and have chest imaging findings to confirm respiratory disease due to COVID-19 within 72 hours of study entry and enrollment. * Supplemental oxygen including but not limited to: nasal cannula, mask, high flow devices, CPAP/BiPAP, invasive mechanical ventilation as well as ECMO. Exclusion Criteria: * Are receiving biologic treatments (such as Tumor Necrosis Factor \[TNF\] inhibitors, interleukin inhibitors, T-cell or B-cell targeted therapies, interferon, or Janus kinase (JAK) inhibitors); or are receiving other immunosuppressants such that, in the opinion of the investigator, participating in the study would put the participant at an unacceptable risk of immunosuppression. Note: A washout period is required prior to screening. * Are receiving strong inhibitors of Organic Anion Transporter 3 (OAT3) (such as probenecid) that cannot be discontinued at study entry. * Have diagnosis of current active tuberculosis (TB) or, if known, latent TB treated for less than 4 weeks with appropriate anti-tuberculosis therapy per local guidelines (by history only, no screening tests required). * Suspected serious, active bacterial, fungal, viral, or other infection (besides COVID-19) that in the opinion of the investigator could constitute a risk when taking investigational product. * Have received any live vaccine within 4 w…