2026 ICD-10-CM Diagnosis Code A37.01Whooping cough due to Bordetella pertussis with pneumonia

ICD-10-CM Codes›A00–B99›A30-A49›A37

ICD-10-CM A37.01
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

A37.01 is a billable ICD-10-CM diagnosis code for whooping cough due to Bordetella pertussis with pneumonia. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 202 through 203. Coders also document this condition as infection caused by Bordetella. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Bacterial infections and Pneumonia (except that caused by tuberculosis).

Code Identity

ICD-10-CM Code
A37.01
Billable Status
Yes — Valid for Submission
Code Describes
Whooping cough due to Bordetella pertussis with pneumonia
Short Description
Whooping cough due to Bordetella pertussis with pneumonia
Same as the full description in the CMS dataset.
Parent Code
A37.0
Whooping cough due to Bordetella pertussis

Code Classification

ChapterA00–B99Certain infectious and parasitic diseases
SectionA30-A49Other bacterial diseases
CategoryA37Whooping cough
This CodeA37.01Whooping cough due to Bordetella pertussis with pneumonia

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Infection caused by Bordetella
  • Pneumonia in pertussis

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Paroxysmal cough due to Bordetella pertussis with pneumonia

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Cough(affected) (epidemic) (nervous)
      • paroxysmal, due to Bordetella pertussis (without pneumonia)
        • with pneumonia
    • Pneumonia(acute) (double) (migratory) (purulent) (septic) (unresolved)
      • in (due to)
        • whooping cough
          • due to
            • Bordetella pertussis
    • Whooping cough
      • with pneumonia
        • due to Bordetella
          • pertussis
    • Whooping cough
      • due to
        • Bordetella
          • pertussis
            • with pneumonia

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR INF003
Bacterial infections
Default principal diagnosis: inpatient Yes · outpatient Yes
CCSR RSP002
Pneumonia (except that caused by tuberculosis)
Default principal diagnosis: inpatient No · outpatient No

Patient EducationClinical

Pneumonia

Pneumonia is an infection in one or both of your lungs. It causes the air sacs of your lungs to fill up with fluid or pus. Pneumonia can range from mild to severe, depending on what caused it, your age, and your overall health.

The full article covers:

  • What is pneumonia?
  • What causes pneumonia?
  • Who is more likely to develop pneumonia?
  • What are the symptoms of pneumonia?
  • What other problems can pneumonia cause?
  • How is pneumonia diagnosed?
  • What are the treatments for pneumonia?
  • Can pneumonia be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert A37.01 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
033.0 Bordetella pertussis
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
484.3 Pneumonia in whoop cough
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About A37.01Overview

Is A37.01 (Whooping cough due to Bordetella pertussis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report whooping cough due to Bordetella pertussis with pneumonia on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does A37.01 group to?

When whooping cough due to Bordetella pertussis with pneumonia is the principal diagnosis on an inpatient stay, it groups to MS-DRG 202, 203, with relative weights from 0.6700 to 0.9712 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of A37.01?

Under the General Equivalence Mappings, whooping cough due to Bordetella pertussis with pneumonia converts to ICD-9-CM 033.0 (bordetella pertussis) and 484.3 (pneumonia in whoop cough). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.