The HSE says its offering a free dose of the MMR vaccine to anyone aged between 11 and 30 amid a significant rise in cases of mumps.
A majority of children get two doses of the vaccine by the time they are 4-5 years of age.
While 91% of children in Ireland have received their first dose of MMR by 24 months of age, it is below the target of 95% to prevent mumps outbreaks and measles cases.
According to the HSE, teenagers and young adults up to 30 years of age have been particularly affected by the current outbreak - with the highest incidences of mumps seen in secondary schools and third-level institutions.
The HSE's Dr Suzanne Cotter said the MMR vaccine is the only way to protect against the disease.
She explained: "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."
Dr Cotted added: "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 noted the vaccine is available free of charge from GPs or through student health services.
Mumps causes symptoms such as facial pain, fever, headache and swelling in front of the ears.
While typically a minor illness, in rare cases it can cause serious complications such as serious brain infection or permanent hearing loss
