Undrdose of pertussis vaccine, inc combin w pertuss, subs

This code signifies that a patient received an insufficient dose of a pertussis-containing vaccine, or did not complete the full vaccination series as recommended. This underdosing could lead to inadequate immunity against whooping cough.

Apply this code when documentation indicates a patient did not receive the full, recommended dose of a pertussis vaccine (e.g., DTaP, Tdap) during a previous encounter, and is presenting for follow-up care related to this underdosing. This is appropriate for subsequent encounters where the underdosing is being addressed or monitored.

• Ensure the documentation clearly states "underdosing" of the pertussis vaccine and specifies it's a subsequent encounter.
• Do not use this code for adverse effects or poisoning from the vaccine; those have different code categories.
• Always sequence this code as a secondary diagnosis, following the code for the condition being treated or the reason for the encounter.