Medical experts have emphasised the importance of the MMR vaccine after a new study showed a sizeable percentage of people who suffer sudden hearing loss had been infected with mumps.
The research also highlighted how the condition, when linked to mumps, did not appear to respond to conventional treatments recommended for sudden hearing loss.
The results of the study, published in the latest edition of the Irish Medical Journal, showed 15% of patients who presented with sudden hearing loss between July 2018 and July 2019 were cases linked to mumps infection.
The study, led by researchers at the Royal Victoria Eye and Ear Hospital in Dublin, found six out of 40 patients who presented at its emergency department with mumps-related sudden hearing loss over the period suffered severe to profound hearing problems.
The average time between the onset of acute hearing loss and presentation was 14 days.
Although all six patients were treated with high-dose steroids for the condition, none showed any improvement in their hearing during a follow-up clinical visit after three months.
One of the authors of the study, Laura McLoughlin of the Department of Otolaryngology at the Royal Victoria Eye and Ear Hospital, said the findings were consistent with other studies which showed the majority of mumps-related cases of hearing loss had a total or profound hearing deficit which failed to recover.
“Sudden sensorineural hearing loss is a significant complication of mumps infection,” said Dr McLoughlin.
While fatalities from the mumps virus is rare, Dr McLoughlin said the infection could also lead to a number of other significant complications including pancreatitis, meningitis, encephalitis, and orchitis.
It is estimated that sudden hearing loss can affect between one per 1,000 and one per 20,000 cases of mumps.
The study said unilateral profound sudden hearing loss is “a debilitating complication” of mumps that does not respond to treatment.
It recommended that the importance of vaccinating against mumps should be emphasised by all medical staff working in the ear, nose, and throat discipline.
The current MMR vaccination rate in Ireland is approximately 91.5% which falls short of the 95% target recommended by the World Health Organisation.
The efficacy of the MMR vaccine in preventing mumps is 88% after the recommended two doses which are administered to children at 12 months followed by a booster at four to five years.
“The MMR vaccine is safe and effective in protecting against the mumps virus and its complications,” said Dr McLoughlin.
She said that hearing loss could have devastating psychological and social impacts on patients including depression and anxiety.
The study noted that Ireland has been experiencing an outbreak of mumps since late 2018. More than 2,600 cases have been reported so far in 2020, more than the entire total for 2019