Pharmacokinetics, Pharmacodynamics, and Safety Profile of Understudied Drugs Administered to Children Per Standard of Care (POPS)

Who May Qualify: 1. Participant is \< 21 years of age 2. Parent/ Legal Guardian/ Adult Participant can understand the consent process and is willing to provide willing to sign a consent form/HIPAA: 3. (a) Participant is receiving one or more of the study drugs of interest at the time of enrollment or (b) Participant is NOT receiving one or more of the study drugs of interest but is SARS-COV-2 positive within 60 days prior to enrollment Who Should NOT Join This Trial: 1. Participant has a known pregnancy Below exclusion criteria apply only to: Participants receiving one or more of the study drugs of interest at the time of enrollment, DOI administration or PK sampling: (Refer to DOI specific appendices for details on enrollment cohort specifications and additional eligibility criteria) 2. Has had intermittent dialysis within previous 24 hours 3. Has had a kidney transplant within previous 30 days 4. Has had a liver transplant within previous 1 year 5. Has had a stem cell transplant within previous 1 year 6. Has had therapeutic hypothermia within previous 24 hours 7. Has had plasmapheresis within the previous 24 hours 8. Has a Ventricular Assist Device 9. Has any condition which would make the participant, in the opinion of the investigator, unsuitable for the study Always talk to your doctor about whether this trial is right for you.