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B97.21 ICD-10-CM Code: SARS-associated coronavirus as the cause of diseases classified elsewhere

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 Excludes1

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v44, Appendix B.

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for B97.21 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Coder workflow for B97.21

MedCoder structured workflow — derived from this code’s own official record

Before you code B97.21

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with B97.21. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in B97.21’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

    ReviewJ12.81

Consider B97.21. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Official instructions as workflow

  • Excludes1 — check before selecting B97.21(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with B97.21: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareJ12.81

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Both the condition B97.21 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

ReviewJ12.81

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse B97.21 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of B97.21 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • J12.81— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of pneumonia due to SARS-associated coronavirus moves the case to J12.81; the two are not reported together unless documented as unrelated.

    Full comparison: B97.21 vs J12.81 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Code Overview

SARS-associated coronavirus as the cause of diseases classified elsewhere is a billable ICD-10-CM diagnosis code (B97.21).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (3)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 1: Certain Infectious and Parasitic Diseases (A00-B99), U07.1, U09.9 a. Human Immunodeficiency Virus (HIV) Infections 1) Code only confirmed cases

b. Infectious agents as the cause of diseases classified to other chapters Certain infections are classified in chapters other than Chapter 1 and no organism is identified as part of the infection code. In these instances, it is necessary to use an additional code from Chapter 1 to identify the organism. A code from category B95, Streptococcus, Staphylococcus, and Enterococcus as the cause of diseases classified to other chapters, B96, Other bacterial agents as the cause of diseases classified to other chapters, or B97, Viral agents as the cause of diseases classified to other chapters, is to be used as an additional code to identify the organism. An instructional note will be found at the infection code advising that an additional organism code is required.

Verify Before Coding

  • Principal-diagnosis restriction. The Medicare Code Editor lists this code as unacceptable as a principal diagnosis: it describes a circumstance influencing health status rather than a current illness or injury being treated. It is valid as a secondary diagnosis.
  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name B97.21 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: B34 — Viral infection of unspecified site (via B97.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 1 Excludes2 note: U07.1 — COVID-19 (via B97.2.-).

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 58 Use Additional Code instructions across 10 chapters: E06.0 — Acute thyroiditis (via B97.-), G06 — Intracranial and intraspinal abscess and granuloma (via B97.-), H65 — Nonsuppurative otitis media (via B97.-), I30.1 — Infective pericarditis (via B97.-), I33.0 — Acute and subacute infective endocarditis (via B97.-), I40.0 — Infective myocarditis (via B97.-), J01 — Acute sinusitis (via B97.-), J02.8 — Acute pharyngitis due to other specified organisms (via B97.-), J03.8 — Acute tonsillitis due to other specified organisms (via B97.-), J04 — Acute laryngitis and tracheitis (via B97.-), J05 — Acute obstructive laryngitis [croup] and epiglottitis (via B97.-), J06.9 — Acute upper respiratory infection, unspecified (via B97.-), J32 — Chronic sinusitis (via B97.-), J36 — Peritonsillar abscess (via B97.-), J37 — Chronic laryngitis and laryngotracheitis (via B97.-), J85 — Abscess of lung and mediastinum (via B97.-), J86 — Pyothorax (via B97.-), J95.851 — Ventilator associated pneumonia (via B97.-), K65 — Peritonitis (via B97.-), K6A.0 — Pelvic abscess (via B97.-), +38 more.

These codes instruct coders to additionally report this code when it applies.

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 133 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 865 (MDC 18), DRG 866 (MDC 18).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):INF008 — Viral infection.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

B34.2 — Coronavirus infection, unspecified, B34.4 — Papovavirus infection, unspecified, B34.8 — Other viral infections of unspecified site, B39.0 — Acute pulmonary histoplasmosis capsulati, B39.1 — Chronic pulmonary histoplasmosis capsulati, B39.2 — Pulmonary histoplasmosis capsulati, unspecified, B44.0 — Invasive pulmonary aspergillosis, B58.3 — Pulmonary toxoplasmosis, B59 — Pneumocystosis, B67.1 — Echinococcus granulosus infection of lung, J09.X1 — Influenza due to identified novel influenza A virus with pneumonia, J09.X2 — Influenza due to identified novel influenza A virus with other respiratory manifestations, J10.00 — Influenza due to other identified influenza virus with unspecified type of pneumonia, J10.01 — Influenza due to other identified influenza virus with the same other identified influenza virus pneumonia, J10.08 — Influenza due to other identified influenza virus with other specified pneumonia, J10.1 — Influenza due to other identified influenza virus with other respiratory manifestations, J11.00 — Influenza due to unidentified influenza virus with unspecified type of pneumonia, J11.08 — Influenza due to unidentified influenza virus with specified pneumonia, J11.1 — Influenza due to unidentified influenza virus with other respiratory manifestations, J12.0 — Adenoviral pneumonia, +113 more

Principal diagnosis restriction (Medicare Code Editor)

Not acceptable as a principal diagnosis on an inpatient claim.

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Viral infection).

+309 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Coronavirus”; these codes share that main term but sit in a different category of the Tabular List.

U07.1 — COVID-19

Contextual Map

Every relationship of B97.21 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run B97.21 with these 11 related codes in Claim Check

Hierarchy

Excludes1

Referenced by Excludes1 notes

Referenced by Excludes2 notes

  • U07.1 — COVID-19[Excludes2](via B97.2.-): “coronavirus as the cause of diseases classified elsewhere (B97.2-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Use Additional Code instructions (58)

Clinical classification (CCSR)

MS-DRG Grouper

  • CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2027
  • DRG 865 — VIRAL ILLNESS WITH MCC[MS-DRG]: “VIRAL ILLNESS WITH MCC (MDC 18)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2027
  • DRG 866 — VIRAL ILLNESS WITHOUT MCC[MS-DRG]: “VIRAL ILLNESS WITHOUT MCC (MDC 18)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2027

MDC crossing

  • MDC 18 — Infectious and Parasitic Diseases, Systemic or Unspecified Sites[MDC crossing]: “Infectious and Parasitic Diseases, Systemic or Unspecified Sites — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 1 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Coronavirus (infection), SARS-associated[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Infection, infected, infective (opportunistic), coronavirus NEC, severe acute respiratory syndrome (SARS associated)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Infection, infected, infective (opportunistic), virus, viral NOS, as cause of disease classified elsewhere, coronavirus, SARS-associated[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (24)

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2027), quoted by section Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v44 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "B97.21 — SARS-associated coronavirus as the cause of diseases classified elsewhere." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/b97.21-sars-associated-coronavirus-as-the-cause-of-diseases-classified-elsewhere

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    SARS-associated coronavirus as the cause of diseases classified elsewhere

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027, and none are recorded for this code. Note changes are tracked from FY2027 only.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to B97.21 in its code family, with their registry titles.

View all codes in the B97 family