Z28.31Header code — not billable
Underimmunization for COVID-19 status
- Chapter
- 21. Factors influencing health status and contact with health services
- Category
- Z28
- Effective date
- October 1, 2026
Related codes in category Z28
Z28Immunization not carried out and underimmunization statusZ28.0Immunization not carried out because of contraindicationZ28.01Immunization not crd out because of acute illness of patientYesZ28.02Immuniz not crd out bec chronic illness or cond of patientYesZ28.03Immuniz not crd out bec immune compromised state of patientYesZ28.04Immuniz not crd out bec patient allergy to vaccine or cmpntYesZ28.09Immunization not carried out because of oth contraindicationYesZ28.1Immuniz not crd out because of patient belief/grp pressrYesZ28.2Immuniz not crd out bec pt decision for oth and unsp reasonZ28.20Immuniz not crd out bec patient decision for unsp reasonYesZ28.21Immunization not carried out because of patient refusalYesZ28.29Immuniz not crd out bec patient decision for oth reasonYes
Frequently asked questions
What is ICD-10 code Z28.31?
Z28.31 is an ICD-10-CM diagnosis code for Underimmunization for COVID-19 status.
Is Z28.31 a billable code?
No. Z28.31 is a category/header code, not billable on its own — use one of its more specific child codes instead.
What ICD-10-CM chapter is Z28.31 in?
Z28.31 falls under Chapter 21: Factors influencing health status and contact with health services.
When did Z28.31 become effective?
Z28.31 has been effective since October 1, 2026, per the CMS/CDC ICD-10-CM annual release.
What other codes are related to Z28.31?
Z28.31 belongs to category Z28, which includes 12 other codes — see the related codes list on this page.
ICD-10-CM data maintained by CDC/CMS (public domain). Always verify codes with authoritative sources before making coding or billing decisions.