2026 ICD-10-CM Diagnosis Code A99Unspecified viral hemorrhagic fever
ICD-10-CM Codes›A00–B99›A90-A99›A99
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Not Chronic
A99 is a billable ICD-10-CM diagnosis code for unspecified viral hemorrhagic fever. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 865 through 866. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 23 closely related codes. Coders also document this condition as viral hemorrhagic fever. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Viral infection.
Code Identity
Code Classification
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Viral hemorrhagic fever
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Viral Hemorrhagic Fever
a group of viral illnesses that are characterized by increased susceptibility to bleeding diatheses.
Patient EducationClinical
Hemorrhagic Fevers
Viral hemorrhagic fevers (VHFs) are a group of illnesses caused by four families of viruses. These include the Ebola and Marburg, Lassa fever, and yellow fever viruses. VHFs have common features: they affect many organs, they damage the blood vessels, and they affect the body's ability to regulate itself.
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Convert A99 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About A99Overview
What is the ICD-10 code for unspecified viral hemorrhagic fever?
The ICD-10-CM code for unspecified viral hemorrhagic fever is A99. It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is A99 (Unspecified viral hemorrhagic fever) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report unspecified viral hemorrhagic fever on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does A99 group to?
When unspecified viral hemorrhagic fever is the principal diagnosis on an inpatient stay, it groups to MS-DRG 865, 866, with relative weights from 0.8696 to 1.4983 depending on complications. Higher weights mean higher Medicare reimbursement.
Is A99 a CC or MCC?
CMS lists A99 as a CC (complication or comorbidity) for FY 2026. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 23 closely related codes in its exclusion list.
What is the ICD-9 equivalent of A99?
Under the General Equivalence Mappings, unspecified viral hemorrhagic fever converts to ICD-9-CM 065.9 (arthropod hem fever NOS). The mapping is approximate, so confirm the match fits the documentation.
