{
  "resourceType": "CodeSystem",
  "status": "draft",
  "content": "complete",
  "name": "NexusAllergenClassCS",
  "id": "nexus-allergen-class",
  "title": "Allergen Class CodeSystem",
  "description": "What kind of thing an allergen is, carried as a second coding on `AllergyIntolerance.code` beside\nthe substance's own SNOMED CT code.\n\nThis determines `AllergyIntolerance.category` rather than duplicating it -- each class maps onto\nexactly one R4 category, and `drug` and `class` both map onto `medication`. That is the point of\nthe system: a reaction to one drug and a reaction to a whole drug class are the same R4 category\nand are not the same fact, and cross-sensitivity checking needs to tell them apart.\n\nRead it by matching `Coding.system`. The substance coding and the class coding share one\n`CodeableConcept` and are in no guaranteed order.",
  "url": "https://fhir.apps.health/CodeSystem/nexus-allergen-class",
  "concept": [
    {
      "code": "drug",
      "display": "Drug",
      "definition": "A single medicinal substance. Maps to `AllergyIntolerance.category` = `medication`."
    },
    {
      "code": "class",
      "display": "Drug class",
      "definition": "A class of medicinal substances rather than one of them -- penicillins, sulfonamides. Maps to `AllergyIntolerance.category` = `medication`, the same category a single drug maps to, which is why the class is recorded here as well: an interaction check against a new prescription has to know whether the recorded reaction covers one product or a family."
    },
    {
      "code": "food",
      "display": "Food",
      "definition": "A food or food constituent. Maps to `AllergyIntolerance.category` = `food`."
    },
    {
      "code": "env",
      "display": "Environmental",
      "definition": "A non-ingested environmental substance -- pollens, latex, animal dander, venoms. Maps to `AllergyIntolerance.category` = `environment`."
    },
    {
      "code": "vaccine",
      "display": "Vaccine",
      "definition": "A vaccine or a vaccine constituent. Maps to `AllergyIntolerance.category` = `biologic`."
    }
  ],
  "experimental": false,
  "caseSensitive": true,
  "count": 5
}