A Fine Gael TD has criticised Facebook for allowing anti-vaccination "propaganda" to be aimed at parents.
Kate O'Connell said they urgently need to address the issue as children's lives are being put at risk.
It comes as the latest figures show from UNICEF that cases of measles in Ireland last year increased by almost 250%, while cases of mumps have also gone up by 540% this year compared to last year.
Both have vaccines that are available, with most children receiving two doses of the MMR (measles, mumps and rubella) vaccine, and Deputy O'Connell said Facebook are feeding into the misinformation.
The Dublin TD, who is also a pharmacist, told Newstalk: "[Anti-vaccination information] has resulted in a decline in vaccination - which we have seen globally, but in Ireland in particular.
"If we see it emerging again to any great extent, we will have reduced herd immunity and [it] will have serious impacts on our population's health."
Any claims of a link between the MMR vaccine and autism have been widely discredited.
In a statement earlier this week, UNICEF Ireland's Peter Power said: “Measles may be the disease, but, all too often, the real infection is misinformation, mistrust and complacency."
Ms O'Connell suggested social media companies should make it very clear to users what is peer-reviewed data and what is opinion or sponsored content.
She added: "I wouldn't be suggesting we try to stop people's freedom of speech, but [instead make sure] that it's very, very clear to users the source of the data."
In a statement last month, Facebook said it had taken steps to "reduce the distribution of health-related misinformation".
However, it admitted it had more to do - adding that it is working on additional changes.
A number of social networks have already taken action against such content.
YouTube confirmed last week that it will not allow ads on videos that "promote anti-vaccination content".