serum sickness; hives; fever; joint pain; swelling in her knee; swelling feet, and hands; difficulty walking; Initial information received on 17-Nov-2022 regarding an unsolicited valid case received from a other health professional.  This case involves a 7 years old female patient who was diagnosed with serum sickness(hives (urticaria) fever (pyrexia) joint pain (arthralgia) swelling in her knee (joint swelling) swelling feet, and hands (peripheral swelling) difficulty walking (gait disturbance) after receiving influenza quadrival a-b  vaccine[Fluzone QIV] and Amoxicillin.  The patient's past medical history, medical treatment(s), concomitant medication(s) and family history were not provided.  On 31-Oct-2022, the patient started taking Amoxicillin (with unknown formulation, frequency, strength, dose, route, lot number and expiration) for unknown indication.  Therapy was stopped on 10-Nov-2022.  On 11-Nov-2022, the patient received a 0.5 ml(milliliter) of influenza quadrival a-b vaccine via intramuscular route in the right arm, for immunization.  On an unknown date, the patient was diagnosed with a serum sickness (had  hives (urticaria) fever (pyrexia) joint pain (arthralgia) swelling in her knee (joint swelling) swelling feet, and hands (peripheral swelling) difficulty walking (gait disturbance) and  (unknown latency) following the administration of influenza quadrival a-b  vaccine  and amoxycillin  It was also reported the patient went to the ER on 13Nov2022, 15Nov2022, and she may have gone again yesterday, 16Nov2022, but the reporter was unable to confirm.the parents told the doctor's office that they think that having the Amoxicillin and the FLUZONE QIV could have caused the serum sickness. The reporter states that the patient is still symptomatic and is coming for follow-up tomorrow, 18Nov2022. Patient Information o Patient age <1 year enter as 2m, 4m, etc. Many pediatric vaccines need month for age. - 7 YEARS Dosage Information o Frequency - ONCE o Therapy Date: From - 11NOV2022 AT 2:40 PM o Route = route & site - IM RIGHT ARM o Dose = 0.25 mL to 2 mL for vaccines or 0.1 mL for TB skin test - 0.5 ML o Strength = standard except for Fluzone High Dose Quadrivalent - STANDARD o Indications = Immunization or TB skin 13NOV2022, 15NOV2022; REPORTER STATES THAT SHE THINKS THE PATIENT WENT TO THE ER A THIRD TIME ON 16NOV2022, BUT SHE WAS UNABLE TO CONFIRM".  Action Taken: Not applicable  The patient was treated with Prednisolone.  At time of reporting, the outcome was Not Recovered / Not Resolved for the event serum sickness.  Seriousness criteria: Medically significant for all events. ; Sender's Comments: Sanofi Company Comment dated 23-Nov-2022: This case involves a 7 years old female patient who was diagnosed with serum sickness(hives (urticaria) fever (pyrexia) joint pain (arthralgia) swelling in her knee (joint swelling) swelling feet, and hands (peripheral swelling) difficulty walking (gait disturbance) after receiving influenza quadrival a-b  vaccine[Fluzone QIV] and Amoxicillin. Based on the limited information provided, the causal role of the company suspect product cannot be excluded in occurrence of the events.The patient was treated with Prednisolone.However, lack of information regarding  any medical history, concomitant medication, concurrent conditions, any family history precludes the comprehensive case assessment. Based upon the reported information, the role of the individual suspect vaccine cannot be assessed.