Sex: M
Vaccine: FLUX
Symptoms: Injection site induration, Injection site pain, Injection site pruritus, Injection site swelling, Type III immune complex mediated reaction
Clinical narrative: Arthus reaction; large swelling at his influenza vaccine injection site on two separate occasions, 13 months apart; painful, indurated, and pruritic swellings at each location within four hours; painful, indurated, and pruritic swellings at each location within four hours; painful, indurated, and pruritic swellings at each location within four hours; interaction between vaccine antigens and pre-existing IgG antibodies; Initial information received on 30-Oct-2024 via Health Care Professional regarding an unsolicited valid serious case issued from a literature article:    This Case was linked to US-SA-2024SA318359.  This case involves a 6-year-old male patient (Patient 1) who experienced Arthus reaction (type iii immune complex mediated reaction) while receiving vaccine Influenza Vaccine (Latency: unknown).  The patient's past medical history, medical treatment(s), vaccination(s) and family history were not provided.  On an unknown date, the patient received a dose of suspect Influenza Vaccine produced by unknown manufacturer lot number not reported via unknown route in unknown administration site.  On an unknown date the patient experienced large swelling at his influenza vaccine injection site on two separate occasions, 13 months apart (Vaccination site swelling). His third dose was divided between two injection sites, yet he developed painful, indurated, and pruritic swellings at each location within four hours (Vaccination site induration) (Vaccination site pruritus) (Vaccination site pain), resolving after three days.   Author stated that: Arthus reaction is a type III hypersensitivity reaction, triggered by interaction between vaccine antigens and pre-existing (immunoglobulin) IgG antibodies (vaccine interaction). Symptoms peak at 12 to 36 hours post-immunization and include injection-site swelling, induration, and pain. Though classically associated with tetanus toxoid boosters, limited literature addresses this phenomenon with other vaccines. This case emphasizes the need for providers to recognize Arthus reactions with vaccines beyond tetanus toxoid. Strategies like dose splitting may not prevent reactions. Recognizing these reactions is crucial for diagnosis, patient management, and counseling. Documenting and reporting these cases will enhance understanding of vaccine safety profiles and inform future clinical guidelines. While current guidelines advise avoiding tetanus vaccines for at least ten years following this reaction, the ideal timing with influenza vaccine is unknown.  Seriousness criteria: medically significant. Action taken: not applicable Corrective treatment: not reported for the event. Outcome: Recovering / Resolving Reporter's causality: Related; Sender's Comments: Sanofi company comment on dated 06-NOV-2024: This case involves a 6-year-old male patient (Patient 1) who experienced Arthus reaction (type iii immune complex mediated reaction) while receiving vaccine Influenza Vaccine. Based on the limited information received the causal role of VACCINE cannot be excluded due to compatible temporal relationship of ADR to the VACCINE. Further information regarding concurrent condition during vaccination, previous vaccination, tolerance, allergic history, laboratory investigations excluding alternative etiologies for the reported event are needed to fully assess this case. Based upon the reported information, the role of vaccine cannot be assessed completely. US-SA-2024SA318359: