2026 ICD-10-CM Diagnosis Code Z20.821Contact with and (suspected) exposure to Zika virus

ICD-10-CM Codes›Z00–Z99›Z20-Z29›suspected

ICD-10-CM Z20.821
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

Z20.821 is a billable ICD-10-CM diagnosis code for contact with and (suspected) exposure to Zika virus. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026). The code is not accepted as a principal diagnosis by the Medicare Code Editor and exempt from POA reporting. Coders also document this condition as exposure to Zika virus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Exposure, encounters, screening or contact with infectious disease.

Code Identity

ICD-10-CM Code
Z20.821
Billable Status
Yes — Valid for Submission
Code Describes
Contact with and (suspected) exposure to Zika virus
Short Description
Contact with and (suspected) exposure to Zika virus
Same as the full description in the CMS dataset.
Parent Code
Z20.82
Contact with and (suspected) exposure to other viral communicable diseases

Code Classification

ChapterZ00–Z99Factors influencing health status and contact with health services
SectionZ20-Z29Persons with potential health hazards related to communicable diseases
CategorysuspectedContact with and exposure to communicable diseases (Z20)
This CodeZ20.821Contact with and (suspected) exposure to Zika virus

Code EditsBilling

Medicare Code Editor checks that affect claim validity for Z20.821.

Unacceptable principal diagnosis
There are selected codes that describe a circumstance which influences an individual's health status but not a current illness or injury, or codes that are not specific manifestations but may be due to an underlying cause. These codes are considered unacceptable as a principal diagnosis.

Present on Admission (POA)Billing

Z20.821 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review other POA exempt codes.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Exposure to Zika virus

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.

    • Contact(with)
      • communicable disease
        • Zika virus
    • Contact(with)
      • Zika virus
    • Exposure(to)
      • communicable disease
        • Zika virus
    • Exposure(to)
      • Zika virus

Clinical ClassificationClinical

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

CCSR FAC016
Exposure, encounters, screening or contact with infectious disease
Default principal diagnosis: inpatient No · outpatient Yes

Patient EducationClinical

Zika Virus

Zika is a virus that is spread mostly by mosquitoes. A pregnant mother can pass it to her baby during pregnancy or around the time of birth. It can spread through sexual contact. There have also been reports that the virus has spread through blood transfusions.

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement Z20.821 replaces the following previously assigned code(s):

  • Z20.828 - Contact w and exposure to oth viral communicable diseases
FY 2019AddedAdded to the ICD-10-CM code setEffective October 1, 2018.
FY 2020–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About Z20.821Overview

Is Z20.821 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report contact with and (suspected) exposure to Zika virus on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Can Z20.821 be a principal diagnosis?

No. The Medicare Code Editor rejects this code as a principal diagnosis because contact with and (suspected) exposure to Zika virus describes a circumstance that influences health status rather than a current illness. Report it as a secondary diagnosis.

Is Z20.821 exempt from POA reporting?

Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for contact with and (suspected) exposure to Zika virus on inpatient claims.