Z28.310 - the Code Designated for the Unvaccinated | 27 Jan 2023 | International Classification of Diseases (ICD) codes are a system used to classify and code diseases, injuries and other health conditions. They are primarily used for tracking and analysing health data, as well as for billing and reimbursement in the healthcare system. Periodically the World Health Organization (WHO) updates the codes to reflect new advances in medical knowledge and technology... Last year, the ICD codes were updated again. However, this time they were updated to record your vaccination status. Code Z28.310 is for the unvaccinated - if the patient has not received at least one dose of any COVID-19 vaccine. Partially vaccinated individuals, those who have received at least one dose of a multi-dose COVID-19 regimen but have not received the full set of doses necessary to meet the CDC definition of "fully vaccinated" in place at the time of the encounter, have been assigned the code Z28.311. They have even designated codes which give the reason why you didn't get vaccinated.