This Literature - Spontaneous case, initially received on 18-Jul-2016, was reported by a health professional and concerns a healthy adult male patient in his 30s. The patient had no known risk factors for hearing loss. Administration of company suspect drug(s): On an unknown date, the patient received Trivalent Inactivated Influenza Virus Vaccine (INN) for indication not reported. Dose regimen: Not reported, Route of administration: Not reported. Batch number: Not reported. No additional suspect drugs. Adverse reactions/events and outcomes: On an unknown date 6 days after receiving the trivalent inactivated influenza vaccine (TIV), the patient presented with sudden onset of right-sided tinnitus and hearing loss. The patient also reported slight, intermittent dizziness but denied fever, congestion or headache. His head and neck examination was normal. The patient had taken an appropriate dosage of ibuprofen for 2 days after TIV for self-limited, non-ear-related pain but stopped two days before the onset of hearing loss. His primary care provider advised decongestants, but these provided no relief of symptoms. The patient was referred to otolaryngology for further evaluation. Audiogram revealed normal hearing in the right ear to 2000 Hz, then a precipitous drop to profound hearing loss in the higher frequencies. Pure tones in the left ear were normal, and tympanograms were type A. Audiology testing performed 6 years earlier was normal bilaterally. Magnetic resonance imaging (MRI) of the brain with and without gadolinium, focused on the internal auditory canal, was normal. He was diagnosed with sudden sensorineural hearing loss (SSHL) and treated with a prednisone taper. His hearing did not improve. Reporter's Comments: Reporter's assessment: The authors concluded that 'a large-scale analysis applying a case-centered method did not detect any association between SSHL and previous receipt of TIV or other vaccines'.  With the 7 years of follow-up, monitoring over 23 million vaccines, the authors found no indication of an increased risk of immunization with any vaccine prior to the development of SSHL. Sender's Comments: Company comments: Listedness: Assessment according to the CCDS for CSL Inactivated Influenza Virus Vaccine, sudden onset sensory neural hearing loss (SSHL) and all other events are unlisted. Causality: Related. There is a plausible time to onset of 6 days following vaccination. Patient had no known risk factors for hearing loss and no (other) secondary cause was found on investigation. Patient's age does not support presence of undiagnosed cardiovascular risk factors tumours and hypercoagulable state. The etiology of SSHL is unknown; autoimmune disease, viral and bacterial infectious diseases have been postulated as potential causes. Of note, the case control study did not find any increased risk of SSHL following TIV vaccinations (7 years of follow-up, monitoring over 23 million vaccines). The authors also noted that temporal association alone does not prove causation when assessing the association of vaccine adverse events. However in this case, a causal association with vaccination cannot be completely excluded due to temporal association and exclusion of alternate etiology. Causality for event pain is unassessable as the anatomical location, description and time to onset following vaccination was not available.