The US Core value set for immunization origin is too ambiguous. http://hl7.org/fhir/valueset-immunization-origin.html

provider Other Provider The data for the immunization event originated with another provider.

record Written Record The data for the immunization event originated with a written record for the patient.

recall Parent/Guardian/Patient Recall The data for the immunization event originated from the recollection of the patient or parent/guardian of the patient.

school School Record The data for the immunization event originated with a school record for the patient.

Need to clarify what to enter for source = IIS, and clarify what is meant by "provider" and "record" - is that to indicate a phone confirmation from a provider Vs a written record? Needs clarification.