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ICD-10 Guide
ICD-10 CodesZ28.31

Z28.31

Underimmunization for COVID-19 status

BILLABLE STATUSYes
IMPLEMENTATION DATEOctober 1, 2015
LAST UPDATED09/12/2025

Code Description

ICD-10 Z28.31 is a billable code used to indicate a diagnosis of underimmunization for covid-19 status.

Key Diagnostic Point:

Z28.31 is used to indicate a patient's underimmunization status specifically related to COVID-19 vaccinations. This code is crucial in understanding the patient's health status, particularly in the context of the ongoing pandemic. Factors influencing underimmunization can include access to healthcare services, socioeconomic status, cultural beliefs, and misinformation about vaccines. Preventive care efforts, such as outreach programs and community education, are essential to address these barriers. Screening for vaccination status during routine health visits allows healthcare providers to identify patients who are underimmunized and facilitate access to vaccines. Aftercare may involve follow-up appointments to ensure patients receive their vaccinations and understand the importance of completing their vaccination series. Proper documentation of these factors is vital for accurate coding and to support public health initiatives aimed at increasing vaccination rates.

Code Complexity Analysis

Complexity Rating: Medium

Medium Complexity

Complexity Factors

  • Variety of factors influencing vaccination status (e.g., socioeconomic, cultural)
  • Need for thorough documentation of patient history and barriers
  • Potential for multiple encounters related to vaccination follow-up
  • Variability in state and local health department guidelines

Audit Risk Factors

  • Inadequate documentation of patient education efforts
  • Failure to capture social determinants affecting vaccination
  • Misalignment between clinical encounters and coding
  • Inconsistent use of Z codes across different providers

Specialty Focus

Medical Specialties

Primary Care

Documentation Requirements

Documentation should include vaccination history, patient education efforts, and any barriers to vaccination encountered during visits.

Common Clinical Scenarios

Routine checkups where vaccination status is assessed, screenings for eligibility for vaccines, and aftercare visits for follow-up vaccinations.

Billing Considerations

Consideration of social determinants such as transportation issues, financial barriers, and cultural beliefs that may affect vaccination uptake.

Public Health

Documentation Requirements

Documentation should focus on population-level data, vaccination rates, and outreach efforts to underimmunized populations.

Common Clinical Scenarios

Epidemiological studies assessing vaccination coverage, community vaccination events, and public health campaigns aimed at increasing vaccination rates.

Billing Considerations

Emphasis on tracking health status and vaccination rates in specific populations, including vulnerable groups.

Coding Guidelines

Inclusion Criteria

Use Z28.31 When
  • Z codes are used to indicate factors influencing health status and contact with health services
  • 31 should be used when a patient is identified as underimmunized for COVID
  • It is important to sequence this code appropriately, often as a secondary diagnosis, following any primary diagnosis related to the patient's visit
  • Payer requirements may vary, so it is essential to verify specific coding guidelines with each payer

Exclusion Criteria

Do NOT use Z28.31 When
No specific exclusions found.

Related CPT Codes

90460CPT Code

Immunization administration (e.g., COVID-19 vaccine)

Clinical Scenario

Used when administering the COVID-19 vaccine to an underimmunized patient.

Documentation Requirements

Documentation of vaccine administration, patient consent, and any counseling provided.

Specialty Considerations

Primary care providers should ensure that all vaccination efforts are documented and linked to Z28.31.

ICD-10 Impact

Diagnostic & Documentation Impact

Enhanced Specificity

ICD-10 Improvements

The transition to ICD-10 has allowed for greater specificity in coding underimmunization statuses, enabling better tracking of vaccination rates and public health initiatives.

ICD-9 vs ICD-10

The transition to ICD-10 has allowed for greater specificity in coding underimmunization statuses, enabling better tracking of vaccination rates and public health initiatives.

Reimbursement & Billing Impact

The transition to ICD-10 has allowed for greater specificity in coding underimmunization statuses, enabling better tracking of vaccination rates and public health initiatives.

Resources

Clinical References

  • •
    CDC COVID-19 Vaccination Guidance

Coding & Billing References

  • •
    CDC COVID-19 Vaccination Guidance

Frequently Asked Questions

What should I document to support the use of Z28.31?

Document the patient's vaccination history, any barriers to vaccination, and the provider's efforts to educate the patient about the importance of vaccination. Include details of any discussions about vaccine safety and follow-up plans.