The RXA segment records what was actually administered to a patient: the substance or vaccine, how much, when it started and ended, who gave it, and the lot and expiration details that matter most for immunizations. Where the order segments say what should happen, RXA says what did happen. It is the core of an immunization (VXU) message and pairs with RXR for the route and site of administration.
Purpose
RXA carries the administration event: the administered code (RXA-5), the amount and units (RXA-6/7), the start and end times (RXA-3/4), the administering provider (RXA-10), and — critical for vaccines — the substance lot number (RXA-15), expiration date (RXA-16), and manufacturer (RXA-17). RXA-18 captures a refusal reason and RXA-20 the completion status, which together distinguish a given dose from a refused or partial one.
Used in
RXA appears in administration-scoped pharmacy and treatment messages: VXU (immunization update — its primary home) and RAS (pharmacy/treatment administration). It is preceded by an order group and almost always followed by an RXR describing route and site. See VXU.
Field-by-field reference
Source: the Vorro HL7 segment database (extracted from the official v2-to-FHIR IG). R = required (cardinality min ≥ 1). Repeat = field may repeat. Length is not carried by the FHIR source and is shown as —.
| Seq | Name | Data Type | Length | Req | Repeat | Table # | Description |
|---|---|---|---|---|---|---|---|
| RXA-1 | Give Sub-ID Counter | nm | — | R | — | — | Links this administration to the give order. |
| RXA-2 | Administration Sub-ID Counter | nm | — | R | — | — | Sequence number for repeated administrations. |
| RXA-3 | Date/Time Start of Administration | dtm | — | R | — | — | When administration began; the occurrence time. |
| RXA-4 | Date/Time End of Administration | dtm | — | R | — | — | When administration ended; equals start if instantaneous. |
| RXA-5 | Administered Code | cwe | — | R | — | HL70292 | What was given; CVX vaccine or drug code. |
| RXA-6 | Administered Amount | nm | — | R | — | — | The dose amount administered. |
| RXA-7 | Administered Units | cwe | — | O | — | — | Units for the administered amount. |
| RXA-8 | Administered Dosage Form | cwe | — | O | — | — | Physical form of the administered substance. |
| RXA-9 | Administration Notes | cwe | — | O | Y | — | Coded notes about the administration. |
| RXA-10 | Administering Provider | xcn | — | O | Y | — | The provider(s) who administered the substance. |
| RXA-11 | Administered-at Location | la2 | — | O | — | — | Location where the substance was administered. |
| RXA-12 | Administered Per (Time Unit) | st | — | O | — | — | Rate time unit for the administration. |
| RXA-13 | Administered Strength | nm | — | O | — | — | Strength of the administered substance. |
| RXA-14 | Administered Strength Units | cwe | — | O | — | — | Units for the administered strength. |
| RXA-15 | Substance Lot Number | st | — | O | Y | — | Lot number of the administered substance. |
| RXA-16 | Substance Expiration Date | dtm | — | O | Y | — | Expiration date of the substance lot. |
| RXA-17 | Substance Manufacturer Name | cwe | — | O | Y | HL70227 | Manufacturer of the administered substance. |
| RXA-18 | Substance/Treatment Refusal Reason | cwe | — | O | Y | — | Why the substance or treatment was refused. |
| RXA-19 | Indication | cwe | — | O | Y | — | Clinical reason the substance was given. |
| RXA-20 | Completion Status | id | — | O | — | HL70322 | Complete, partial, refused, or not administered. |
| RXA-21 | Action Code – RXA | id | — | O | — | — | Add, update, or delete this administration record. |
| RXA-22 | System Entry Date/Time | dtm | — | O | — | — | When the record was entered in the system. |
| RXA-23 | Administered Drug Strength Volume | nm | — | O | — | — | Volume of the administered drug strength. |
| RXA-24 | Administered Drug Strength Volume Units | cwe | — | O | — | — | Units for the drug strength volume. |
| RXA-25 | Administered Barcode Identifier | cwe | — | O | — | — | Barcode identifier of the administered product. |
| RXA-26 | Pharmacy Order Type | id | — | O | — | — | Pharmacy or treatment order type. |
| RXA-27 | Administer-at | pl | — | O | — | — | Structured location where administered. |
| RXA-28 | Administered-at Address | xad | — | O | — | — | Address of the administration location. |
| RXA-29 | Administered Tag Identifier | ei | — | O | Y | — | Tag identifier(s) for the administered product. |
Most-used fields
- RXA-5 Administered Code is what was given — for immunizations the CVX vaccine code that drives the FHIR
vaccineCode. Almost every consumer branches on it. - RXA-3 Date/Time Start of Administration is the occurrence time registries record and de-duplicate on.
- RXA-15 Substance Lot Number and RXA-16 Substance Expiration Date are required by most immunization registries for recall and inventory tracking.
- RXA-17 Substance Manufacturer Name (MVX-coded) pairs with the lot for vaccine provenance.
- RXA-20 Completion Status separates a completed dose (
CP) from a refusal (RE) or not-administered (NA), which flips the FHIRstatus.
Version differences (2.3 to 2.8.2)
- 2.3/2.4: RXA established for pharmacy/treatment administration; core give and timing fields present.
- 2.5: coded fields move from
CEtowardCWE; RXA-20 Completion Status and RXA-21 Action Code clarified. - 2.7+: RXA-23 through RXA-29 (drug strength volume, barcode, pharmacy order type, structured administer-at location and address, tag identifier) added.
- Receivers built for 2.3 ignore the trailing fields they do not recognize.
Common mistakes
- Sending the administered amount in RXA-6 but omitting RXA-7 units, leaving the dose ambiguous.
- Dropping RXA-15/16 lot number and expiration, which immunization registries reject or flag.
- Confusing RXA-20
CP(completed) with a refusal — a refused dose needsREplus RXA-18. - Forgetting the partner RXR: route and site live there, not in RXA.
- Reading only the first repetition of RXA-10 when multiple administering providers are listed.
Examples
Minimal valid RXA (only the required fields):
RXA|0|1|20260610103000|20260610103000|08^Hep B, adolescent or pediatric^CVX|0.5
Fully-populated RXA (administered influenza vaccine):
RXA|0|1|20260610103000|20260610103000|140^Influenza, seasonal, injectable^CVX|0.5|mL^milliliter^UCUM|||1234^JONES^MARY^^^^RN||||||L20260A|20271231|SKB^GlaxoSmithKline^MVX||||CP|A|20260610104500
Annotated breakdown of the fully-populated example (selected fields):
RXA ← segment ID
0 ← RXA-1 Give Sub-ID Counter
1 ← RXA-2 Administration Sub-ID Counter
20260610103000 ← RXA-3 Date/Time Start of Administration
20260610103000 ← RXA-4 Date/Time End of Administration
140^Influenza, seasonal, injectable^CVX ← RXA-5 Administered Code (CVX)
0.5 ← RXA-6 Administered Amount
mL^milliliter^UCUM ← RXA-7 Administered Units
1234^JONES^MARY^^^^RN ← RXA-10 Administering Provider
L20260A ← RXA-15 Substance Lot Number
20271231 ← RXA-16 Substance Expiration Date
SKB^GlaxoSmithKline^MVX ← RXA-17 Substance Manufacturer Name
CP ← RXA-20 Completion Status (Complete)
A ← RXA-21 Action Code (Add)
20260610104500 ← RXA-22 System Entry Date/Time
In-context inside a VXU^V04 (immunization update), RXA with RXR following:
MSH|^~&|EHR|MERCYGEN|IIS|STATE|20260610104500||VXU^V04^VXU_V04|MSG200|P|2.5.1
PID|1||MR12345^^^MERCYGEN^MR||DOE^JOHN^Q||20150101|M
ORC|RE||IZ001^MERCYGEN
RXA|0|1|20260610103000|20260610103000|140^Influenza, seasonal, injectable^CVX|0.5|mL^milliliter^UCUM|||1234^JONES^MARY^^^^RN||||||L20260A|20271231|SKB^GlaxoSmithKline^MVX||||CP
RXR|IM^Intramuscular^HL70162|LD^Left Deltoid^HL70163
In-context inside a VXU^V04 recording a refused dose (RXA-18 + RXA-20 RE), RXR omitted as nothing was administered:
MSH|^~&|EHR|MERCYGEN|IIS|STATE|20260610110000||VXU^V04^VXU_V04|MSG201|P|2.5.1
PID|1||MR12345^^^MERCYGEN^MR||DOE^JOHN^Q||20150101|M
ORC|RE||IZ002^MERCYGEN
RXA|0|1|20260610110000|20260610110000|03^MMR^CVX|999|||||||||||||00^Parental refusal^NIP002||RE
FHIR mapping
Primary target resource: Immunization. The official ConceptMap is RXA to Immunization.
Key Immunization mappings:
| RXA field | FHIR target (Immunization) |
|---|---|
| RXA-3 Date/Time Start of Administration | occurrenceDateTime |
| RXA-5 Administered Code | vaccineCode (CodeableConcept) |
| RXA-6 Administered Amount | doseQuantity.value |
| RXA-7 Administered Units | doseQuantity (SimpleQuantity) |
| RXA-10 Administering Provider | performer.actor (Practitioner), performer.function = AP |
| RXA-15 Substance Lot Number | lotNumber |
| RXA-16 Substance Expiration Date | expirationDate |
| RXA-17 Substance Manufacturer Name | manufacturer (Organization) |
| RXA-18 Substance/Treatment Refusal Reason | statusReason (CodeableConcept) |
| RXA-19 Indication | reasonCode (CodeableConcept) |
| RXA-20 Completion Status | status (CP → completed, via CompletionStatus vocab) |
| RXA-21 Action Code | status (entered-in-error) |
| RXA-22 System Entry Date/Time | recorded |
| RXA-27 Administer-at | location (Location) |
| RXA-28 Administered-at Address | location (Location.address) |
RXA-10 also sets performer.function.coding.system to http://terminology.hl7.org/CodeSystem/v2-0443. Fields without a published Immunization mapping — RXA-1/2 (sub-ID counters), RXA-4 (end time), RXA-8/9, RXA-11/12/13/14, RXA-23 through RXA-26, and RXA-29 — are pharmacy/administration details not represented on Immunization.
Engine considerations
- Required in practice: RXA-3, RXA-5, and RXA-6 are essential; immunization interfaces also effectively require RXA-15/16/17 for registry acceptance.
- Treat RXA-5 as a structured
CWEso the CVX code, text, and coding system survive — registries match on the code, not the text. - Honor RXA-20: a
CPbecomes Immunizationstatus=completed, whileRE/NAplus RXA-18 must not be emitted as a completed dose. - Preserve repeating fields (RXA-9/10/15/16/17/18/19/29) as arrays.
- Keep the RXA/RXR pairing intact — route and site come from the following RXR.
How Vorro parses and produces RXA
Vorro maps RXA-5 to Immunization vaccineCode, RXA-3 to occurrenceDateTime, and RXA-15/16/17 to lotNumber, expirationDate, and manufacturer for registry submission. RXA-20 drives the FHIR status (with RXA-18 captured as statusReason on a refusal), administering providers in RXA-10 are emitted as performer with function AP per the official ConceptMap, and the following RXR is carried through so route and site reach Immunization.route and site.
Related pages
- RXR — the route and site that complete an RXA administration.
- RXE — the pharmacy/treatment encoded order RXA reports against.
- VXU messages — where RXA carries immunization administrations.
