Over 250 cases of mumps have already been notified to the HSE so far in 2020, with secondary schools and third level institutions recording the highest incidences of the disease.

Mumps is a highly infectious viral illness, which is spread easily from person to person. Symptoms include fever, headache and swollen, tender salivary glands, which can give the appearance of a swollen jaw or swollen cheeks.

"Mumps is a highly infectious and dangerous illness which spreads very easily, particularly in homes, crèches, playgroups, camps, schools and universities. It can be a serious illness and can have life changing repercussions in some instances," explained Dr Suzanne Cotter, a public health specialist with the HSE Health Protection Surveillance Centre (HPSC).

During 2019, the number of mumps cases hit 2,762 compared with 573 cases in 2018. Just three weeks into 2020, 253 cases have already been recorded.

Children aged 11-18 and adults aged up to 30 have been particularly affected by this mumps outbreak. Those in the 15-19 age group have been worst affected so far this year, with 94 cases already, followed by 88 cases in the 20-24 age group.

In response to this, the HSE is offering a free dose of the MMR vaccine to people aged between 11 and 30. It is urging anyone in this age group who has not had two doses of the MMR vaccine, or who is unsure of their vaccine status, to avail of the offer.

According to Dr Cotter, the MMR vaccine "is the only way to protect against mumps".

"The vaccine also protects against measles and rubella. In Ireland, the first MMR dose is given at 12 months of age, and the second dose at 4-5 years of age.

"Parents must make sure that their children and teenagers are protected against mumps by ensuring they have been immunised with two doses of MMR. A third dose of MMR won't cause any harm so anyone unsure of whether they have had two doses or not, can safely receive the vaccine again," she explained.

She urged parents and young adults to speak with their GP or student health service, and get the vaccine free of charge.