Anaphylactic reaction due to vaccination, initial encounter

This code signifies a severe, life-threatening allergic reaction (anaphylaxis) that occurs as a direct result of receiving a vaccination. It involves a rapid onset of symptoms such as widespread hives, swelling, difficulty breathing, and a drop in blood pressure, requiring immediate medical intervention.

Apply this code when a patient presents with clear signs and symptoms of anaphylaxis immediately following or very shortly after vaccine administration. This includes reactions to any type of vaccine (e.g., flu, tetanus, COVID-19) where anaphylaxis is the confirmed adverse event. This code is appropriate for the initial treatment of such an event.

• Always sequence this code first if it is the primary reason for the encounter.
• Ensure documentation clearly links the anaphylaxis to the vaccination event.
• Do not use this code for less severe allergic reactions; those would be coded differently.