At least 336 people suffered hearing loss in Japan in 2015 and 2016 as a result of complications related to the contraction of mumps, a survey by an ear, nose and throat society showed Wednesday.

The findings, underlining the need for free public vaccinations, saw a total of 261 people diagnosed with severe hearing loss to such an extent that it causes difficulties in their daily lives. Of sufferers, 154 were aged between 5 and 10 years old, according to the survey by the Oto-Rhino-Laryngological Society of Japan, which drew responses from 3,536 medical institutions across the country.

Fourteen patients developed hearing difficulties in both ears and 11 began wearing hearing aids or had a cochlear device implanted, the society said.

Those in their 30s made up a relatively large number of mumps sufferers, it added.

Mumps is a viral disease which can see patients develop fever and swelling in the salivary glands under the ear. Vaccinations were formerly conducted regularly in Japan, but mandatory inoculations were halted in 1993 after their side-effects came to public attention.

Currently, vaccinations are conducted on a voluntary basis with recipients or recipients' guardians shouldering the cost.

"Among developed countries, Japan is the only nation without routine vaccinations for the disease," the society said, urging the government to resume a regime of free vaccinations.