3 syringes with loose plunger rods /The 3rd time it was being administered; it was being administered and became loose / fell out with the liquid syringe / had to use another one to administer the vaccine; it was being administered and became loose / fell out with the liquid syringe; This case was reported by a nurse via sales rep and described the occurrence of accidental underdose in a 51-year-old male patient who received Flu Seasonal QIV Quebec (FluLaval Tetra 2020-2021 season) (batch number 99J23, expiry date 30th June 2021) for prophylaxis. This case was associated with a product complaint.   Co-suspect products included flu seasonal qiv quebec pre-filled syringe device (Flulaval Tetra Pre-Filled Syringe Device) injection syringe for prophylaxis.   On 9th October 2020, the patient received FluLaval Tetra 2020-2021 season and Flulaval Tetra Pre-Filled Syringe Device. On 9th October 2020, unknown after receiving FluLaval Tetra 2020-2021 season and Flulaval Tetra Pre-Filled Syringe Device, the patient experienced accidental underdose and syringe issue. On an unknown date, the patient experienced pharmaceutical product complaint. On an unknown date, the outcome of the accidental underdose, syringe issue and pharmaceutical product complaint were unknown.     This report is made by GSK without prejudice and does not imply any admission or liability for the incident or its consequences.   Additional Information: The reporter stated information about 3 syringes with loose plunger rods on 3 separate occasions. She only had the lot number for the most recent incident as it was during administration that the plunger became loose. At first and second time it happened, it was discovered upon preparing. The nurse took it out and was preparing and the plunger rod fell out. The second time, it looked like it became unscrewed and the nurse screwed it back but it was wobbly and she did not feel comfortable using it. The 3rd time, it was being administered and became loose and fell out with the liquid syringe. The nurse had to use another one to administer the vaccine, which led to syringe issue. The reporter took another syringe to vaccinate the patient which led to accidental underdose.  All three syringes had been discarded. It was reported that this happened at different times with 3 different nurses and different lot numbers. The reporter consented to follow up. An investigation had been conducted, including review of the reported defect trends, the retained samples and our production records, which has demonstrated that the subject batch was produced in compliance with the applicable procedures and met all required specifications. Plunger rod detachment was a known issue due to technical limits such as height variability of plunger stopper positioning during filling process and limited control of the adequateness of plunger rod screwing along the process. Following the recurrence of this type of complaints, some actions had been identified and implemented in order to improve our process. These actions contributed to the decrease of complaints describing loose plunger rods. However, GlaxoSmithKline cannot rule out that plungers could become loose because of vibrations during subsequent operations and transportations or during the preparation of the administration of the vaccine. Therefore, GlaxoSmithKline considers this complaint as substantiated. Before using the syringe, GlaxoSmithKline would like to recommend the customer to check the screwing of the plunger rod inside the stopper, and, if required, to manually screw it. It should lead to solve this kind of problem. Conclusion of the QA statement was received as follows. GlaxoSmithKline Biological considered this complaint as substantiated. The VAERS details were updated   Follow-up receipt date: 4-Aug-2022. This follow-up was considered significant. QA comment: Executive summary and conclusions of the QA statement were received as follows: customer reported a complaint which falls within the following product technical complaint category: loose plunger rod based on the defect description. An investigation had been conducted, including review of the reported defect trends, the retained samples and our production records, which had demonstrated that the subject batch was produced in compliance with the applicable procedures and met all required specifications. Plunger rod detachment was a known issue due to technical limits such as height variability of plunger stopper positioning during filling process and limited control of the adequateness of plunger rod screwing along the process. Following the recurrence of this type of complaints, some actions had been identified and implemented in order to improve our process. These actions contributed to the decrease of complaints describing loose plunger rods. However, GlaxoSmithKline cannot rule out that plungers could become loose because of vibrations during subsequent operations and transportations or during the preparation of the administration of the vaccine. Therefore, GlaxoSmithKline considers this complaint as substantiated. Before using the syringe, GlaxoSmithKline would like to recommend the customer to check the screwing of the plunger rod inside the stopper, and, if required, to manually screw it. It should lead to solve this kind of problem. The sterility of the vaccines is not adversely impacted by a loose plunger rod and the issue was easily detectable by healthcare professionals. In the event of a vaccine leakage during the attempt to administer a vaccine dose with a loose plunger rod, resulting in the administration of a partial dose of vaccine to a patient (i.e., patient underdosing), the healthcare professionals would be able to detect the leakage (and the associated loose plunger rod) and make appropriate decisions based on the local or CDC guidance on revaccination should they determine that only a partial dose was administered. The revaccination of the patient in the event of a leak would then mitigate against the risk of reduced efficacy following the administration of the initial partial dose. Based on the review of the adverse event cases co-reported with complaints of loose plunger rods received from May 2019 to May 2022, the risk of adverse impact on efficacy of the vaccination is unlikely. Moreover, the sterility of the vaccine was not affected by the loose plunger rod defect. In conclusion, if the health care professional had inadvertently used a syringe with a loose plunger rod for vaccination, it was unlikely that such a usage would adversely affect patient safety. The GlaxoSmithKline Biologicals considered the complaint that was the object of this report as substantiated. Summary of changes: Device details and Narrative details updated