Z28.310 – Unvaccinated for COVID-19

The ICD-10-CM code Z28.310 designates a patient as someone “unvaccinated for COVID-19.” Learn what this code entails, from its clinical information, if it’s billable or not, FAQs, and even related ICD-10 codes by reading this short guide.

By Ashleigh Knowles on Aug 8, 2025.

Fact Checked by Ericka Pingol.

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Z28.310 Diagnosis Code: Unvaccinated for COVID-19

The Z28.310 is an ICD code that’s included in the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM), and it is used to designate “Unvaccinated for COVID-19.”

This ICD-10 code is actually considered to be unacceptable as a principal diagnosis. This specific type of ICD code is employed to classify a patient who is experiencing a particular condition that affects their present health status, but this condition is not an illness or injury they are currently managing. This code is primarily used to indicate the absence of COVID-19 immunization, which is a common inquiry made by healthcare providers and professionals in current times.

Is Z28.310 billable?

Yes, the Z28.310 ICD-10 code is billable and can be used to designate a patient for reimbursement purposes.

Z28.310 clinical information:

The Z28.310 ICD-10 code is part of a group of codes meant o represent a patient’s current health status. These codes are normally the designations listed and reported first during a patient’s medical care journey with a provider.

In the cotext of this particular ICD-10 code, it signifies that the patient has not received the COVID-19 vaccination. Consider a scenario where a patient is undergoing a routine check-up without any specific illness or injury. This check-up may be required for work purposes (such as annual physical examination requirements) or simply as a proactive measure to monitor their overall health. If, during the consultations, you discover that the patient has not been vaccinated against COVID-19, you can utilize this code.

Do note that this code is different from Z28.31, which is for designating the patient as underimmunized for COVID-19. While it sounds similar to this code, it isn’t. Underimmunized in this context means that they are vaccinated, but not fully.

Z28.310 synonyms include:

Not vaccinated for COVID-19
Not immunized for COVID-19

Other ICD-10 codes commonly used for COVID-19:

Z28.31 - Underimmunization for COVID-19 status
Z28.311 - Partially vaccinated for COVID-19

Commonly asked questions

Yes, this ICD-10 code is billable.

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It’s best to use this if your patient is undergoing a check-up or a circumstance affecting their health (but not tied to a current illness or injury). If you find out they are not vaccinated for COVID-19, use this code.

This is more of a health status than an illness or injury. The only way to “solve” it is to get vaccinated, but the patient has a choice to get vaccinated or not. Best to educate them on why it’s best to get vaccinated.

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