Live attenuated measles and mumps viral strain-containing vaccines and hearing loss: Vaccine Adverse Event Reporting System (VAERS), United States, 1990--2003.

Hearing loss (HL) is a known complication of wild measles and mumps viral infections. As vaccines against measles and mumps contain live attenuated viral strains, it is biologically plausible that in some individuals HL could develop as a complication of vaccination against measles and/or mumps. Our objectives for this study were: to find and describe all cases of HL reported in the scientific literature and to the US Vaccine Adverse Events Reporting System (VAERS) for the period 1990--2003; and to determine reporting rate of HL after live attenuated measles and/or mumps viral strain-containing vaccines (MMCV) administration. We searched published reports for cases of HL identified after vaccination with MMCV. We also searched for reports of HL after MMCV administration submitted to VAERS from 1990 through 2003 and determined the dose-adjusted reporting rate of HL. Our main outcome measure was reported cases of HL after immunization with MMCV which were classified as idiopathic. We found 11 published case reports of HL following MMCV. The review of the VAERS reports identified 44 cases of likely idiopathic sensorineural HL after MMCV administration. The onset of HL in the majority of VAERS and published cases was consistent with the incubation periods of wild measles and mumps viruses. Based on the annual usage of measles-mumps-rubella (MMR) vaccine, we estimated the reporting rate of HL to be 1 case per 6-8 million doses. Thus, HL following MMCV has been reported in the literature and to the VAERS. Further studies are needed to better understand if there is a causal relationship between MMCV and HL.