Sex: M
Vaccine: FLUX, FLUX, FLUX
Symptoms: Pain, Scan with contrast normal, Sudden hearing loss, Tinnitus, Tympanometry
Clinical narrative: Case number PHHY2016US103588 is an initial literature report received on 25 Jul 2016. The author discussed about a study conducted using case centered method, equivalent to a case control design to assess an epidemiological association between immunizations and Sudden-Onset Sensorineural Hearing Loss (SSHL). This report refers to a healthy male patient who was in his thirties. He received an inactivated trivalent influenza vaccine (TIV, manufacturer and batch number: not reported) on an unknown date. He presented with sudden onset of right sided tinnitus and hearing loss 6 days after receiving the vaccine. The patient reported slight, intermittent dizziness but denied fever, congestion or headache, and he had no known risk factors for hearing loss. His head and neck examination was normal. The patient had taken an appropriate dose of ibuprofen for 2 days after TIV for self-limited, non-ear related pain, but it was stopped 2 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 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. Word recognition scores were 100% in both ears, 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 SSHL and treated with a prednisone taper. At the time this case occurred, intratympanic steroids were not commonly used and oral steroids alone were the standard of care. It was reported that his hearing did not improve. The outcome of tinnitus and lightheadedness was not reported. The seriousness of the events was not reported by the reporter, but the event SSHL was upgraded as medically significant based on the NVS-IME list. Because of the temporal association between the SSHL and immunization, the patient's otolaryngologist brought this case to the attention of Centers of Disease Control and Preventions (CDC's) Clinical Immunization Safety Assessment (CISA) Project to assess whether there might be a causal association between the receipt of TIV and onset of SSHL. In 2014, CISA contracted with healthcare system to pilot application of case-centered analytic methods to assess whether specific vaccine adverse events might be associated with an increased likelihood of receipt of one or more vaccines during a risk interval and hence a case centered analysis using immunization dates from all matched members of the population to calculate exposure to vaccines, rather than sampling was performed within healthcare system to assess the epidemiological association between immunization and SSHL. The healthcare system databases from 2007 to 2013 were searched for all first time diagnoses of SSHL. As illustrated in the presenting case, a diagnosis of SSHL was often delayed until the patient was seen by an otolaryngologist. For this reason, to better identify the date of symptom onset, all diagnoses during the 60 days prior to the diagnosis of SSHL were first searched and from among those, the diagnoses that could possibly have been related or been a precursor to an SSHL diagnosis were chosen. During the study period, greater than 20 million vaccines were administered at healthcare system and all vaccines for which over 20,000 doses were given at healthcare system in the 7 year study period were examined. In the healthcare system databases, a total of 1929 cases of SSHL within 9 months of any vaccine were detected. Of those 57 (3.0%) were within 1 week of a vaccine. All 50 randomly selected SSHL cases were verified by chart review as new incident cases. In all risk intervals prior to onset of SSHL, no evidence of increased risk of immunization compared to matched controls was found. The author stated that the review of the 13 VAERS reports of SSHL following TIV seemed to indicate the possibility of clustering in time of SSHL with respect to TIV vaccination; however, temporal association did not prove causation when assessing the association of vaccine adverse events. The author stated that their application of case-based statistical methods clearly demonstrated no clustering of either TIV or any other vaccine prior to the outcome of SSHL. The author concluded the article stating 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.