Underdosing of smallpox vaccines, initial encounter

This code signifies that a patient received less than the prescribed or recommended dose of a smallpox vaccine. This underdosing could lead to insufficient immunity against the variola virus, potentially leaving the patient vulnerable to infection.

Apply this code when documentation indicates a patient did not receive the full, intended dose of a smallpox vaccine during the initial encounter for this specific underdosing event. This may occur if the vaccine administration was interrupted, an incorrect volume was given, or the patient did not complete the full vaccination series as initially planned.

• Ensure documentation clearly specifies "underdosing" and identifies the vaccine as a "smallpox vaccine."
• The 7th character "A" indicates an initial encounter for the underdosing event itself, not necessarily the first time the patient received any smallpox vaccine.
• Consider co-reporting with codes for any adverse effects or reasons for underdosing, if applicable and documented.