This is the CodeSystem that contains codes in both BeCSVaccineTargetDisease (https://www.ehealth.fgov.be/standards/fhir/vaccination/CodeSystem/be-cs-vaccine-target-disease) and BeCSVaccineTargetDisease (https://www.ehealth.fgov.be/standards/fhir/vaccination/CodeSystem/be-cs-vaccine-target-disease).