VXU^V04 — Unsolicited Vaccination Record Update

The message that pushes a vaccination to the registry: injected dose, lot, site, route. Pivot of US Immunization Information Systems (IIS) and regional registries.

Purpose

VXU^V04 transmits a vaccine administration performed in an EHR to an IIS (Immunization Information System): regional or national registry, CDC base. The message carries:

• patient identity (PID), with local MRN AND IIS identifier;
• order context (ORC);
• actual vaccination (RXA): CVX code, lot, manufacturer, date;
• administration route (RXR): IM, SC, intranasal, oral;
• eligibility metadata, information source, VIS published date.

In the US, this message is mandatory for most vaccine acts performed in pediatric practices and VFC (Vaccines for Children) programs.

Segment structure

VXU_V04
  MSH                    Message Header (mandatory)
  [ SFT ]                Software Segment
  PID                    Patient Identification (mandatory)
  [ PD1 ]                Patient Additional Demographics
  [ { NK1 } ]            Next of Kin
  [ { GT1 } ]            Guarantor
  [ { IN1 [IN2] [IN3] } ] Insurance
  {                      Order block (mandatory, repeatable)
    ORC                  Common Order
    [
      RXA                Pharmacy Administration (mandatory)
      [ RXR ]            Pharmacy Route
      [ { OBX } ]        Observation/Result
    ]
  }

MSH — Message Header

• MSH-9: VXU^V04^VXU_V04.
• MSH-21: profile identifier — typically Z22^CDCPHINVS in the US (Z22 profile).

PID — Patient Identification

Critical for IIS: two identifiers typically expected in PID-3:

• local MRN (type CX, ^^^HOSP^MR);
• IIS identifier if already assigned (type CX, ^^^IIS^SR) to enable merging.

ORC / RXA — Order / Pharmacy Administration

• ORC-1: order control code (RE=Observation to follow).
• ORC-3: filler identifier (IIS-side).
• RXA-3: administration date.
• RXA-5: vaccine code — CVX (CDC table, e.g. 115=Tdap, 207=Moderna COVID-19, 208=Pfizer COVID-19).
• RXA-6: administered dose.
• RXA-7: unit (mL, UCUM).
• RXA-9: information source (NIP001 table: 00=New record, 01=Historical record from parent).
• RXA-10: administrator (XCN).
• RXA-15: lot number (with manufacturer qualifier).
• RXA-16: vaccine expiration date.
• RXA-17: manufacturer (MVX, CDC table: SANOFI, PFR=Pfizer, MOD=Moderna).
• RXA-21: administration status (A=Active, R=Refused).

RXR — Pharmacy Route

• RXR-1: route (table 0162: IM=Intramuscular, SC=Subcutaneous, PO=Oral).
• RXR-2: site (table 0163: LD=Left Deltoid, RD=Right Deltoid).

OBX — Observation (informationSource, refusalReason)

OBX carries eligibility and documentation metadata:

• OBX-3: LOINC code (e.g. 64994-7=Vaccine funding eligibility, 29768-9=Date VIS published).
• OBX-5: value (VFC status, VIS date).

Real-world example

Patient John Doe vaccinated Tdap (Sanofi, lot LOT12345) on 15 May 2026, IM route, left deltoid, VFC-eligible:

MSH|^~\&|EHR|CLINIC02|IIS|REGION01|20260515103000||VXU^V04^VXU_V04|MSG00006001|P|2.5.1|||AL|NE|||||Z22^CDCPHINVS
PID|1||MRN567890^^^HOSP^MR~12345^^^IIS^SR||DOE^JOHN^A^^MR.||19720515|M|||100 MAIN ST^^ANYTOWN^CA^90210^USA||(555)555-1234
ORC|RE||IIS-2026-001^IIS||CM||||20260515103000|^Clinical^||DRJONES^Jones^Sarah^^^DR.^^^HOSP01|||||CLINIC02
RXA|0|1|20260515|20260515|115^Tdap^CVX|0.5|mL^^UCUM||00^New immunization record^NIP001|DRJONES^Jones^Sarah|||||LOT12345^^^^^FRYY|20281231|SANOFI^Sanofi^MVX|||||CP||||||A
RXR|IM^Intramuscular^HL70162|LD^Left Deltoid^HL70163
OBX|1|CE|64994-7^Vaccine funding program eligibility category^LN|1|V05^VFC eligible - federally qualified health center patient^HL70064||||||F|||20260515
OBX|2|TS|29768-9^Date vaccine information statement published^LN|1|20240407||||||F|||20260515

Acknowledgment (ACK)

MSH|^~\&|IIS|REGION01|EHR|CLINIC02|20260515103001||ACK^V04^ACK|ACK00006001|P|2.5.1
MSA|AA|MSG00006001

Common errors

• RXA-5 without CVX: using a proprietary code instead of CVX makes the message non-interoperable with US IIS.
• Missing manufacturer (RXA-17): the manufacturer is required for pharmacovigilance and correlation with VAERS reports.
• Missing lot and expiration: on a lot recall, impossible to trace exposed patients.
• RXA-9 = historical source without documentation: a parent-reported dose must have RXA-9 = 01 and ideally an OBX history of immunization.
• Refusal without coded reason: RXA-21 = R without an OBX refusalReason (LOINC 30945-0) is non-auditable.

FHIR equivalent

In FHIR R5, the VXU^V04 equivalent is the Immunization resource, with fields vaccineCode (CVX), lotNumber, expirationDate, manufacturer, route, site, doseQuantity, and performer. The vaccination forecaster is carried by ImmunizationRecommendation.