ICD-10-CM 2027 diagnosis code

B01Varicella [chickenpox]

Not billable — use a more specific code

B01 is a header code, so it can't be reported by itself. Choose one of the 5 more specific codes beneath it.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About B01

B01 is the ICD-10-CM diagnosis code for varicella [chickenpox]. It belongs to block B00-B09 (viral infections characterized by skin and mucous membrane lesions) and chapter 1 (certain infectious and parasitic diseases). It is a header code, so it can't be reported by itself; one of its 5 subcodes must be used instead.

To report this condition, pick the subcode that matches the documentation: B01.0 (meningitis), B01.1 (encephalomyelitis), B01.2 (pneumonia), B01.8 (complications) and B01.9 (complication).

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Specific codes under B01

Notes that apply from higher levels

Instructions written at a parent level also apply to B01.

Broader instructions also apply from Chapter 1: Certain infectious and parasitic diseases.

Codes whose notes reference B01

B10Excludes2
B10Excludes2

Code history

2016
2017
2018
2019
2020
2021
2022
2023
2024
2025
2026
2027

FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
No changes since FY2016.

Common questions about B01

Is B01 billable?: No. B01 is a header code. Report one of its more specific subcodes instead.