> ## Documentation Index
> Fetch the complete documentation index at: https://docs.connectivehealth.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Immunization

> The FHIR Immunization resource as produced by Connective Health

[FHIR R4 Immunization](https://www.hl7.org/fhir/R4/immunization.html) ·
[US Core Immunization](https://hl7.org/fhir/us/core/STU9/StructureDefinition-us-core-immunization.html)

<Info>
  This resource is produced identically for the [Patient Everything](/fhir/patient-everything-bundle) and
  [Patient Summary](/fhir/patient-summary-bundle) bundles. It is not produced for
  [Bulk Medication History](/fhir/bulk-medication-history-bundle).
</Info>

# Stable ID

The `id` is derived from the patient, the administration date, and the vaccine code. Two administrations of the same
vaccine on the same day therefore resolve to a single `Immunization`.

# Fields

| Field                | Cardinality | Notes                                                                                                                |
| -------------------- | ----------- | -------------------------------------------------------------------------------------------------------------------- |
| `meta.profile`       | 1..1        | Always set to the US Core Immunization profile URL.                                                                  |
| `status`             | 1..1        | Always `completed`. Only administered vaccines are published -- not-done and entered-in-error records do not appear. |
| `patient`            | 1..1        | Reference to the [Patient](/fhir/resources/patient).                                                                 |
| `vaccineCode`        | 1..1        | A single coding for the vaccine, usually [CVX](http://hl7.org/fhir/sid/cvx).                                         |
| `occurrenceDateTime` | 1..1        | The date the vaccine was administered.                                                                               |

<Note>
  US Core requires `occurrenceDateTime` on every `Immunization`. Source immunizations with no administration date are
  excluded from the bundle entirely, rather than being published without one.
</Note>

<Note>
  `primarySource`, `lotNumber`, `expirationDate`, `site`, `route`, `doseQuantity`, `performer`, `encounter`, and
  `statusReason` are not populated -- the source data for immunizations carries only the vaccine, the date, and the
  fact that it was given.
</Note>