During flu season, we administer many flu vaccinations. However, in this isolated event, during administration of Fluarix Flu Vaccine, with lure lock needle there was a product defect. When I was screwing on the needle, I felt a click, so I visually made sure that the needle was threaded correctly. The needle was on the syringe correct and was in a snug positing. When I went to administer the vaccine into the right deltoid, the liquid vaccine leaked down the arm of the patient. None or a very minimal amount actually got injected through the needle into the muscle. I disposed of the needle properly. I reached out to pharmacy to see how I should proceed. The manufacturer of the Fluarix vaccine was contacted, as well.