As she was pulling back the syringe, there was blood in it, darker blood indicating a vein was hit; Patient claimed to be able to "taste the vaccine"; It seems the needle may have gotten into her vessel and there is the possibility a tiny, minuscule amount went into the bloodstream; This spontaneous case was received on 03-Oct-2023, with additional information received on 05-Oct-2023 (being processed together) from a pharmacist via Company (reference number: SEQW23-02906) and concerned a female patient of unspecified age.  The patient's medical history and concomitant medications were not reported.  On 03-Oct-2023, it was attempted to immunize a patient with Afluria Quadrivalent (influenza vaccine inact split 4v) for active immunization against influenza disease caused by influenza virus subtypes A and B present in the vaccine. As the Healthcare practitioner (HCP) was pulling back the syringe, there was blood in it, darker blood indicating a vein was hit. The dose was not given as the nurse simply took the vaccine out of the patient's deltoid, once she saw the blood, and did not push the plunger. It seemed the needle may have gotten into the patient's vessel and there was the possibility a tiny, minuscule amount went into the bloodstream (explicitly coded as 'Product administration error').  As reported, they did not notice any damage in the needle or the syringe and they used a one-inch needle, appropriate for a thin person as in the case. The nurse stated that it was in the muscle, but it must have hit a vein there. The patient was a thin person, not a heavy person. The batch number reported was AU4543A and expiry date 30-Jun-2024.  On the same date, after possibility of a tiny, minuscule amount of the Afluria Quadrivalent went into the bloodstream, the patient claimed to be able to taste the vaccine. The patient had no complaint other than the taste.  The reporter did not provide a causality assessment.  The event of venous injury was considered to be medically significant by a Physician within CSL Seqirus's Pharmacovigilance Department.  Company comment: A female patient of unspecified age was vaccinated with the suspect product Afluria Quadrivalent. As the Healthcare practitioner (HCP) was pulling back the syringe, there was blood in it, darker blood indicating a vein was hit. It seemed the needle may have gotten into the patient's vessel and there was the possibility a tiny amount went into the bloodstream (explicitly coded as 'Product administration error'). As reported the patient claimed to be able to taste the vaccine. Causality for product administration error is assessed as not related based on company specific guidelines. Causality for venous injury and dysgeusia is assessed as not related due to biological implausibility.; Sender's Comments: A female patient of unspecified age was vaccinated with the suspect product Afluria Quadrivalent. As the Healthcare practitioner (HCP) was pulling back the syringe, there was blood in it, darker blood indicating a vein was hit. It seemed the needle may have gotten into the patient's vessel and there was the possibility a tiny amount went into the bloodstream (explicitly coded as 'Product administration error'). As reported the patient claimed to be able to taste the vaccine. Causality for product administration error is assessed as not related based on company specific guidelines. Causality for venous injury and dysgeusia is assessed as not related due to biological implausibility.