leaking syringe while administering FUZONE HD PFS; part of dose leaked out of syringe on to patient's arm when plunger was pushed down,  no adverse event; leaking syringe while administering FUZONE HD PFS; part of dose leaked out of syringe on to patient's arm when plunger was pushed down,  no adverse event; leaking syringe while administering FUZONE HD PFS; part of dose leaked out of syringe on to patient's arm when plunger was pushed down,  no adverse event; Initial information regarding an unsolicited valid non-serious case was received from a pharmacist via Medical Information (Reference number- 00768655) and transmitted to Sanofi on 14-Sep-2021.  This case involves a 76-year-old female patient who experienced leaking syringe while administering INFLUENZA QUADRIVAL A-B HIGH DOSE HV VACCINE [FLUZONE HIGH-DOSE QUADRIVALENT], part of dose leaked out of syringe on to patient's arm when plunger was pushed down [(incorrect dose administered), (exposure via skin contact) and (syringe issue)].  The patient's medical history, past medical treatment(s), vaccination(s) and family history were not provided.  Information of concomitant medications was not reported.  On 14-Sep-2021, the patient received a dose of suspect INFLUENZA QUADRIVAL A-B HIGH DOSE HV VACCINE (lot number: UJ702AC; expiry date: 30-Jun-2021; form: pre-filled syringe) via intramuscular route in the left deltoid for prophylactic vaccination.  It was case of actual medication error due to incomplete dose administered, exposure via skin contact and syringe leak (latency: same day).  It was reported "Pharmacist reports leaking syringe while administering FUZONE HD PFS; part of dose leaked out of syringe on to patient's arm when plunger was pushed down, pharmacist paused injection and checked tightness of connector and needle, then pushed plunger down again and a few drops leaked on to his glove"  The reporter mentioned, leaking did not come from barrel and it was coming from where it connects with luer adaptor narrowing between luer lock adaptor and barrel. Further the reporter mentioned, less than half the dose leaked, approximately 3 drops on patient's arm, and some drops on caller's glove. There were no signs of damage or tampering with the vial, stopper, flip seal or carton.  The reporter had used PFS (pre-filled syringes) from same box on patient's husband just prior and had no issues. Also, the syringe did not look dropped or damaged. The caller checked syringe and needle and it was screwed on correctly. The caller had used same needle tips all day without issue. The reporter requested information on revaccination as he did not know how much vaccine the patient received and would like to know if any other issues had been reported.  The reporter stated that the syringe was discarded in sharps container and was not available for the return. The reporter was advised that if the customer states picture(s) were available, ask to send us the picture(s).  No adverse events were reported at the time of this report.  The outcome of the events was reported as unknown.  This suspected adverse reaction report is submitted and classified as a medication error solely and exclusively to ensure the marketing authorization holder's compliance with the requirements set out in the Directive 2001/83/EC and Module VI of the Good Pharmacovigilance Practices. The classification as a medical error is in no way intended, nor should it be interpreted or construed as an allegation or claim made by the marketing authorization holder that any third party has contributed to or is to be held liable for the occurrence of this medication error.