This is the ValueSet that contains all the codes in Non-Negative Immunization Status (http://hl7.org/fhir/us/qicore/ValueSet/qicore-non-negative-immunization-status) and Immunization Status Codes (http://hl7.org/fhir/ValueSet/immunization-status). E.g. what you have to deal with if you get resources containing codes in either of them