Union of http://terminology.hl7.org/CodeSystem/reaction-event-certainty and http://terminology.hl7.org/CodeSystem/reaction-event-certainty

This is the CodeSystem that contains all the codes in AllergyIntoleranceCertainty (http://terminology.hl7.org/CodeSystem/reaction-event-certainty) and AllergyIntoleranceCertainty (http://terminology.hl7.org/CodeSystem/reaction-event-certainty). E.g. what you have to deal with if you get resources containing codes in either of them

CodeSystem

Generated Narrative: CodeSystem 818959f7-0f8d-4f6f-b46c-7c5a5833d862-791

This code system http://hl7.org/fhir/comparison/CodeSystem/818959f7-0f8d-4f6f-b46c-7c5a5833d862-791 defines codes, but no codes are represented here

CodeDisplayDefinition
unlikely UnlikelyThere is a low level of clinical certainty that the reaction was caused by the identified substance.
likely LikelyThere is a high level of clinical certainty that the reaction was caused by the identified substance.
confirmed ConfirmedThere is a very high level of clinical certainty that the reaction was due to the identified substance, which may include clinical evidence by testing or rechallenge.
unknown UnknownThe clinical certainty that the reaction was caused by the identified substance is unknown. It is an explicit assertion that certainty is not known.