Immunization — Administered vaccination

The record of a vaccine dose: product, lot, route, site, vaccination series. Key resource for vaccination passports and registries.

Purpose of the resource

Immunization documents the actual administration of a vaccine dose to a patient. Not to be confused with ImmunizationRecommendation (calendar-driven recommendation) or MedicationRequest (prescription). Immunization is a past event: the dose was injected, or refused (status=not-done), at a specific time and location.

Typical use cases: electronic vaccination record, national immunisation registry (REIVAC in France, IIS in the US), digital vaccine passport (DCC / EU Digital Covid Certificate, SMART Health Cards), epidemiological reporting and pharmacovigilance.

Key fields

Vaccine code systems

JSON example

COVID-19 booster (3^rd dose) Pfizer-BioNTech administered on 14 May 2026 to Patient "example", left arm, IM, 0.3 mL dose, lot EM0477:

{
  "resourceType": "Immunization",
  "id": "covid-booster",
  "status": "completed",
  "vaccineCode": {
    "coding": [{
      "system": "http://hl7.org/fhir/sid/cvx",
      "code": "208",
      "display": "COVID-19, mRNA, LNP-S, PF, 30 mcg/0.3 mL dose"
    }, {
      "system": "http://snomed.info/sct",
      "code": "1119349007",
      "display": "Severe acute respiratory syndrome coronavirus 2 mRNA vaccine"
    }]
  },
  "administeredProduct": {
    "concept": {
      "coding": [{
        "system": "http://hl7.org/fhir/sid/ndc",
        "code": "59267-1000-3",
        "display": "Pfizer-BioNTech COVID-19 Vaccine"
      }]
    }
  },
  "manufacturer": {
    "reference": { "reference": "Organization/pfizer" }
  },
  "lotNumber": "EM0477",
  "expirationDate": "2026-11-30",
  "patient": { "reference": "Patient/example" },
  "encounter": { "reference": "Encounter/vaccination-visit" },
  "occurrenceDateTime": "2026-05-14T14:30:00+01:00",
  "primarySource": true,
  "location": { "reference": "Location/pharmacy-001" },
  "site": {
    "coding": [{
      "system": "http://terminology.hl7.org/CodeSystem/v3-ActSite",
      "code": "LA",
      "display": "Left arm"
    }]
  },
  "route": {
    "coding": [{
      "system": "http://terminology.hl7.org/CodeSystem/v3-RouteOfAdministration",
      "code": "IM",
      "display": "Intramuscular"
    }]
  },
  "doseQuantity": {
    "value": 0.3,
    "unit": "mL",
    "system": "http://unitsofmeasure.org",
    "code": "mL"
  },
  "performer": [{
    "function": {
      "coding": [{
        "system": "http://terminology.hl7.org/CodeSystem/v2-0443",
        "code": "AP",
        "display": "Administering Provider"
      }]
    },
    "actor": { "reference": "Practitioner/nurse-001" }
  }],
  "protocolApplied": [{
    "series": "COVID-19 booster",
    "targetDisease": [{
      "coding": [{
        "system": "http://snomed.info/sct",
        "code": "840539006",
        "display": "Disease caused by Severe acute respiratory syndrome coronavirus 2"
      }]
    }],
    "doseNumberPositiveInt": 3
  }]
}

• status=completed and primarySource=true: data captured by the vaccinator, source of truth.
• vaccineCode dual-coded CVX (USA) + SNOMED CT (international) for maximum interop.
• administeredProduct NDC specifies the exact brand.
• lotNumber EM0477 + expirationDate for pharmacovigilance (in case of a Pfizer lot recall).
• protocolApplied.doseNumberPositiveInt=3 indicates this is the 3^rd dose of the series.

REST API

• GET /Immunization?patient=Patient/example — full immunisation history.
• GET /Immunization?patient=Patient/example&status=completed&_sort=-date — recent doses sorted by date.
• GET /Immunization?vaccine-code=208&date=ge2026-01-01 — all COVID Pfizer doses since 1 Jan 2026 (regional registry).
• POST /Immunization — create after vaccination.
• GET /Immunization?lot-number=EM0477 — search by lot (pharmacovigilance).
• GET /Patient/example/$everything?_type=Immunization,AllergyIntolerance — composite for vaccination visit.

National profiles

Common pitfalls

• CVX / NDC confusion — CVX codes the vaccine (antigen and general context), NDC codes the specific pharmaceutical product (brand + dosage + packaging). Always carry both for full traceability.
• Missing lotNumber — without a lot number, impossible to respond to a pharmacovigilance signal or lot recall.
• Wrong primarySource — if the dose was transcribed from a paper record, set false. Otherwise registry data-quality analytics wrongly count it as primary source.
• Missing protocolApplied — for multi-dose vaccines (COVID, HPV, hep B), forgetting doseNumberPositiveInt makes it impossible to compute schedule completion.
• Refusal encoded as absence — a refused vaccination must be encoded with status=not-done + statusReason, not by absence of an Immunization resource. Otherwise "never offered" cannot be distinguished from "explicitly refused".
• Free-text occurrence — avoid occurrenceString except when the date is fully unknown (legacy paper card import).

Related resources

• ImmunizationRecommendation — calendar-driven recommendations.
• ImmunizationEvaluation — evaluation of a dose against the schedule.
• Medication — referenced pharmaceutical product.
• AllergyIntolerance — contraindication to check beforehand.
• Observation — documented post-vaccination reactions.
• Patient — vaccinated subject.