ICD-10-CM Z20-Z29 Code Range

Persons with potential health hazards related to communicable diseases (Z20-Z29) ICD-10-CM

The Z20–Z29 section covers persons with potential health hazards related to communicable diseases with 85 ICD-10-CM diagnosis codes, of which 65 are billable in fiscal year 2026. The section is organized into the 6 code ranges listed below.

✓ Built from the official CMS FY 2026 datasetEffective Oct 1, 2025 – Sep 30, 2026

Code Ranges

Diagnosis Codes

Billable Codes

Z20–Z29

Code Range

Code Range	Title	Codes	Billable
Z20	Contact with and (suspected) exposure to communicable diseases (Z20)	23	18
Z21	Asymptomatic human immunodeficiency virus [HIV] infection status (Z21)	1	1
Z22	Carrier of infectious disease (Z22)	26	20
Z23	Encounter for immunization (Z23)	1	1
Z28	Immunization not carried out and underimmunization status (Z28)	23	17
Z29	Encounter for other prophylactic measures (Z29)	11	8

Title

Codes

Billable

Z20

Contact with and (suspected) exposure to communicable diseases (Z20)

Z21

Asymptomatic human immunodeficiency virus [HIV] infection status (Z21)

Z22

Carrier of infectious disease (Z22)

Z23

Encounter for immunization (Z23)

Z28

Immunization not carried out and underimmunization status (Z28)

Z29

Encounter for other prophylactic measures (Z29)

About the Z20–Z29 Code Range

The ICD-10-CM codes in the Z20-Z29 range are used to document individuals who have been exposed to or are carriers of communicable diseases, as well as those receiving immunizations or prophylactic treatments. These codes help specify contact with infectious agents, carrier status of infections, immunization encounters, underimmunization, and preventative healthcare measures.

Codes from Z20 cover suspected or confirmed exposure to specific infectious diseases like tuberculosis, rabies, HIV, and various bacterial and viral infections including COVID-19 and varicella. For example, exposure to Escherichia coli is coded under Z20.01, while Z20.822 is reserved for suspected or confirmed exposure to SARS-CoV-2. The Z21 code addresses asymptomatic HIV infection. Carrier status codes under Z22 reflect individuals harboring infectious agents such as typhoid (Z22.0), staphylococci (Z22.32), or sexually transmitted infections (Z22.4). Immunization encounter codes start at Z23, indicating when vaccines like influenza or HPV have been administered. Codes in Z28 denote cases where immunizations were not given or are incomplete due to patient choice, medical contraindications, or other reasons, including refusal of COVID-19 vaccines. Finally, Z29 codes are for encounters involving prophylactic therapies like immune globulins or HIV pre-exposure prophylaxis. These codes provide detailed documentation supporting disease prevention and public health tracking.

Questions About This Page

How many codes are in the Z20-Z29 range?

The Z20-Z29 range contains 85 ICD-10-CM diagnosis codes in FY 2026. 65 of them are billable, and the rest are category headers that organize the section.

What conditions does Z20-Z29 cover?

The range covers persons with potential health hazards related to communicable diseases. The code ranges listed above break it into groups of related conditions, and each one links to its own page with the full code list.

Related References

Source: CMS FY 2026 ICD-10-CM Tabular List and order file, effective October 1, 2025 through September 30, 2026.

Contact with and (suspected) exposure to communicable diseases (Z20)

Inside this range

Z20Contact with and (suspected) exposure to communicable diseases

Type 1 Excludes

A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.

carrier of infectious disease Z22
diagnosed current infectious or parasitic disease -see Alphabetic Index

Type 2 Excludes

A type 2 excludes note represents "Not included here". An excludes2 note indicates that the condition excluded is not part of the condition represented by the code, but a patient may have both conditions at the same time. When an Excludes2 note appears under a code, it is acceptable to use both the code and the excluded code together, when appropriate.

personal history of infectious and parasitic diseases Z86.1

Open Z20 →

Asymptomatic human immunodeficiency virus [HIV] infection status (Z21)

Inside this range

Z21Asymptomatic human immunodeficiency virus [HIV] infection status

Inclusion Terms

These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.

HIV positive NOS

Code First

Certain conditions have both an underlying etiology and multiple body system manifestations due to the underlying etiology. For such conditions, the ICD-10-CM has a coding convention that requires the underlying condition be sequenced first followed by the manifestation. Wherever such a combination exists, there is a "use additional code" note at the etiology code, and a "code first" note at the manifestation code. These instructional notes indicate the proper sequencing order of the codes, etiology followed by manifestation.