A84.1 ICD-10-CM Code: Central European tick-borne encephalitis
HCC Buddy Code Card
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FY 2026 Apr update / Certain infectious and parasitic diseases (A00-B99) / Viral and prion infections of the central nervous system (A80-A89)
A84.1
Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidanceCentral European tick-borne encephalitis
A viral infection transmitted by tick bites that causes inflammation of the brain, occurring primarily in Central Europe.
CMS-HCC V28
N/A—
Not mapped
CMS-HCC V24
N/A—
Not mapped
ACA/HHS
MappedHCC 3
Varies by metal level
ESRD/PACE
N/A—
Not mapped
RXHCC
N/A—
Not mapped
Code Book Path
Inclusion Terms
OfficialICD-10-CM does not list inclusion terms for A84.1 in this effective period.
Excludes 2
OfficialICD-10-CM does not list Excludes 2 notes for A84.1 in this effective period.
Related Child Codes
Includes
Official- tick-borne viral meningoencephalitis
Excludes 1
OfficialICD-10-CM does not list Excludes 1 notes for A84.1 in this effective period.
Code First
OfficialICD-10-CM does not list Code First sequencing instructions for A84.1 in this effective period.
Use Additional
OfficialICD-10-CM does not list Use Additional Code instructions for A84.1 in this effective period.
Code Also
OfficialICD-10-CM does not list Code Also instructions for A84.1 in this effective period.
Buddy Documentation Tip
Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.
Is A84.1 an HCC code?
No. A84.1 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
Coder workflow notes
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This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
A84.1 is the ICD-10-CM diagnosis code for central european tick-borne encephalitis. A viral infection transmitted by tick bites that causes inflammation of the brain, occurring primarily in Central Europe. A84.1 sits in the ICD-10-CM chapter for certain infectious and parasitic diseases (a00-b99), within the section covering viral and prion infections of the central nervous system (a80-a89).
A84.1 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
Verify the geographic exposure history to Central Europe to confirm this specific tick-borne encephalitis variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for A84.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.