Pediatric Coding Alert

And take note of these new COVID-19 underimmunization codes.

There’s a lot more to using the Z23 (Encounter for immunization) and Z28.- (Immunization not carried out and underimmunization status) codes than meets the eye.

Here’s how you can navigate these codes, along with a rundown of the new COVID-19 underimmunization codes to keep your immunization encounter coding current.

Understand How to Use Z23

If a patient’s immunization goes ahead without an issue, using Z23 (Encounter for immunization) is a no-brainer. But notes for the code tell you that you need to use Z23 in conjunction with numerous other ICD-10 and CPT^® codes.

The first note tells you to “Code first any routine childhood examination,” which is consistent with ICD-10 guideline I.C.21.c.2, telling you to code Z23 as “a secondary code if the inoculation is given as a routine part of preventive health care, such as a well-baby visit.”

Code this: A 1-month-old infant returns to your practice for a well-baby check, which reveals no abnormal findings. During the visit, your pediatrician counsels the infant’s mother about the safety of the hepatitis B vaccine before administering the first dose of the vaccine. As the guideline also tells you that “procedure codes are required to identify the types of immunizations given,” coding for the encounter, including the correct ICD-10 code sequencing, should look something like this:

ICD-10:

• Z00.129 (Encounter for routine child health examination without abnormal findings)
• Z23
• Z71.85 (Encounter for immunization safety counseling)

CPT^®:

• 99391 (Periodic comprehensive preventive medicine reevaluation and management of an individual including … infant (age younger than 1 year))
• 90460 (Immunization administration through 18 years of age via any route of administration, with counseling by physician or other qualified health care professional; first or only component of each vaccine or toxoid administered)
• 90744 (Hepatitis B vaccine (HepB), pediatric/adolescent dosage, 3 dose schedule, for intramuscular use)

When to use Z71.85: ICD-10 guideline I.C.21.c.10 tells you that the code only applies “for counseling of the patient or caregiver regarding the safety of a vaccine” (emphasis added,) which is what the pediatrician did in this encounter. The guideline also tells you that the code “should not be used for the provision of general information regarding risks and potential side effects during routine encounters for the administration of vaccines.”

Understand the Nuances of Z28.-

Things get a little more complex when a patient or guardian either cannot, or will not, be immunized. But rationales for a patient not to get vaccinated essentially boil down to the three reasons reflected in the Z codes:

Unvaccinated due to health reasons: Document this with “the Z28.0 [Immunization not carried out because of contraindication] range, depending on what type of sickness the patient has,” says JoAnne M. Wolf, RHIT, CPC, CEMC, coding manager at Children’s Health Network in Minneapolis.

“Two codes that are commonly used in this situation, again depending on your pediatrician’s determination of the patient’s condition, are Z28.01 [Immunization not carried out because of acute illness of patient] and Z28.02 [… because of chronic illness or condition of patient],” suggests Donelle Holle, RN, president of Peds Coding Inc., and a healthcare, coding, and reimbursement consultant in Fort Wayne, Indiana. Depending on circumstances, you could also use:

• Z28.03 (Immunization not carried out because of immune compromised state of patient)
• Z28.04 (Immunization not carried out because of patient allergy to vaccine or component)
• Z28.81 (Immunization not carried out due to patient having had the disease)

Unvaccinated due to philosophical/religious reasons: Your application of Z28.82 (Immunization not carried out because of caregiver refusal) and Z28.21 (Immunization not carried out because of patient refusal) if your patient is old enough to make their own wishes known is also pretty straightforward.

But you should note the American Academy of Pediatrics’ (AAP’s) advice before using Z28.1 (Immunization not carried out because of patient decision for reasons of belief or group pressure), which notes that the code’s inclusion term, “Immunization not carried out because of religious belief,” indicates that it can be used with or without the patient’s consent. (See AAP Pediatric Coding Newsletter Volume 11, Issue 11 at coding.solutions.aap.org/article.aspx?articleid=2536853).

And if the patient or caregiver declines the immunization without a specified reason, you’ll reach for Z28.9 (Immunization not carried out for unspecified reason).

Unvaccinated because the vaccine is unavailable: Synonyms for Z28.83 (Immunization not carried out due to unavailability of vaccine) tell you to use the code in the event that the vaccine is unavailable or delayed because of manufacturing or delivery problems.

Understand When to Use Z28.3

ICD-10 does not tell you how or when to apply Z28.3 (Underimmunization status). So, you will need to defer to your pediatrician before using it. Chances are, they will consult an immunization schedule, such as the one provided by the Centers for Disease Control and Prevention (CDC) at www.cdc.gov/vaccines/schedules/downloads/child/0-18yrs-child-combined-schedule.pdf, to make the determination.

And Remember These New COVID-19 Underimmunization Codes

Earlier this year, the Centers for Medicare & Medicaid Services (CMS) added three new codes to the Z28.3- group, effective April 1, 2022, to provide information about your patients’ COVID-19 immunization status:

• Z28.310 (Unvaccinated for COVID-19)
• Z28.311 (Partially vaccinated for COVID-19)
• Z28.39 (Other underimmunization status)

To use the codes correctly, follow AHA ICD-10-CM Coding Clinic advice, which tells you to use additional Z28.0- codes mentioned earlier “to provide further information on reasons for underimmunization.” Additionally, the Coding Clinic cautions you not to use a Z28.31- code “for individuals who are not eligible for the COVID-19 vaccines, as determined by the healthcare provider.” This includes many of your very young patients who are currently too young for the vaccine (AHA ICD-10-CM Coding Clinic, 2022, Vol. 9, No. 1).