This is the CodeSystem that contains codes in both AllergyIntoleranceCertainty (http://terminology.hl7.org/CodeSystem/reaction-event-certainty) and AllergyIntoleranceCertainty (http://terminology.hl7.org/CodeSystem/reaction-event-certainty).
This code system http://hl7.org/fhir/comparison/CodeSystem/2c77c26f-0eba-4543-89eb-09eda3cba01c-1497 defines codes, but no codes are represented here
| Code | Display | Definition |
| unlikely | Unlikely | There is a low level of clinical certainty that the reaction was caused by the identified substance. |
| likely | Likely | There is a high level of clinical certainty that the reaction was caused by the identified substance. |
| confirmed | Confirmed | There 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 | Unknown | The clinical certainty that the reaction was caused by the identified substance is unknown. It is an explicit assertion that certainty is not known. |