RSV immunisations will be available to newborns and babies aged up to six months old and the programme will run over the winter, the Minister for Health has said.
The immunisation will be offered in maternity hospitals to all babies born between 1 September this year and 28 February next year.
It will also be available to babies aged less than six months old on 1 September, to offer them protection ahead of the expected seasonal upsurge in infection with RSV in the coming months.
For babies born between 1 March and 31 August this year, appointments will be available during September until the first week in October.
Appointments can be booked online from 25 August for this group.
RSV (respiratory syncytial virus) is a common virus that causes coughs and colds.
The HSE said almost all children get the virus by the time they are two years old, adding that it is the main cause of bronchiolitis and pneumonia in very young children.
Most symptoms are mild, such as a runny nose, coughing and sneezing and recovery usually lasts two to three weeks without treatment or the need to see a GP.
However, four in every 100 newborn babies are hospitalised due to RSV each winter, with some needing special treatment in intensive care units.
Almost 22,500 infants were immunised against RSV last year with an uptake rate of approximately 83% overall.
There was an estimated 65% reduction in the number of RSV cases throughout the winter season when compared with 2023-2024, the Department of Health said.
The Deputy Chief Medical Officer Professor Ellen Crushell said a winter immunisation programme will be a "real game changer for paediatrics".
Speaking to RTÉ's News At One, Prof Crushell said: "We are very excited with the announcement that the campaign is starting now."
"Every winter a lot of babies get sick, a lot of them can be managed at home but a lot of them will also need GP and hospital visits.
"A small percentage will actually need ICU," she added.
"Until last year, every winter the pressure on beds because of babies with RSV occupying beds throughout the country in paediatric units has a knock on on bed availability, on sometimes procedures and other elective work has to get cancelled because of the pressure on beds," she said.
Prof Crushell also stressed that it can cause similar pressure on ICU beds at the height of the season.
"Those immunisations will be given in the community at local community clinics which will be run by the HSE," Prof Crushell added.
She said that parents will be able to access an online portal from next week in order to book an appointment, with further details to be released by the HSE.
"I would urge people to get it soon because it is a temporary immunisation, a temporary protection. It lasts for about 150 days, ideally everybody should get it in September.
"RSV starts to circulate in September and incidences rise then over the following couple of months," the deputy chief medical officer added.
Minister Jennifer Carroll MacNeill said there was an estimated 57% reduction in emergency department presentations, 76% reduction in hospitalisations and a 65% reduction in ICU admissions for RSV-related illnesses last year.
"For new parents, knowing their baby is protected against a potentially serious illness has brought immense reassurance," she said.
She encouraged all parents to "take up this opportunity to safeguard their child's health".
The RSV immunisation programme uses the monoclonal antibody nirsevimab, which the HSE said is not the same as a vaccine.
While vaccines stimulate the immune system to produce antibodies, nirsevimab gives the antibodies directly to the immunised individual.
"Nirsevimab works straight away so your baby is protected as soon as they get immunised," the HSE said.
Nirsevimab is safe and it is more than 80% effective at protecting babies from hospitalisation due to complications of RSV infection, the HSE says.
It protects newborns against RSV for 150 days and protects them when their risk of severe infection is high.
