RSV immunisation for babies
What is RSV (respiratory syncytial virus?)
RSV is a common virus that causes respiratory infections. In young babies, symptoms include a runny nose, temperature, cough and wheezing.
The risk of severe infection is highest in the youngest infants, especially those born during the RSV season in winter. Each winter in Ireland one in two babies will get RSV and many will need medical care from their GP or the emergency department of a children’s hospital. Four out of a hundred babies are hospitalised due to RSV, with some babies needing special treatment in intensive care units.
What is nirsevimab?
Nirsevimab is a monoclonal antibody. An antibody is a special protein that helps fight off infections. A monoclonal antibody is one that has been made in a laboratory to fight off a specific infection.
Who is the RSV immunisation being offered to?
It is recommended for all babies aged six months or less at the beginning of September and those born during the RSV season (typically from September to February).
How will the immunisation programme be delivered?
This is happening in two ways. For the newborn babies, the programme will be delivered in all maternity settings in the Republic of Ireland after the baby is born and before the baby is discharged from hospital.
For babies aged six months or less by beginning of September, an appointment for immunisation can be booked. Appointments will be available up to 17 October 2025 and must be booked before 10 October 2025.
Why is the HSE offering extending the programme to cover more babies than it did in 2024?
Nirsevimab immunisation is recommended by the National Immunisation Advisory Committee (NIAC) for all infants born during the RSV season (typically from September to February), ideally before discharge from the maternity hospital. This group of children is described as a ‘birth cohort'. This programme was implemented in Ireland for the first time in autumn/winter 2024/25.
Nirsevimab is also indicated for infants aged six months or less at the start of the RSV season and ideally before the season begins. This group of children is described as a ‘catch-up cohort’ and immunisation is offered from end of August to beginning of October. This programme is delivered in Ireland for the first time from autumn/winter 2025/26.
Nirsevimab is also indicated for other groups of infants with underlying health conditions or who are immunocompromised or with other conditions including prematurity. This group of children is described as ‘higher risk infants’. Nirsevimab was used to treat this group of children in Ireland for the first time in autumn/winter 2024/25.
What happens to babies born outside of these dates?
The programme is aimed to protect the most vulnerable babies and infants at the time when risk of exposure to RSV is highest. Before late September /early October and after February, there is usually little or no RSV circulating in Ireland. Therefore, this protection is not required. Parents and guardians are however strongly advised to have their infants immunised when the service is offered as once infants are discharged from hospital following birth and when the community immunisation clinics are stood down, there will not be other opportunities to get immunised.
If your child is not eligible for RSV immunisation, the risk of RSV infection can be reduced by:
- cleaning hands properly
- avoiding crowded places
- limiting contact with people who have cold-like symptoms or other infections
Information on preventing RSV infection is available at https://www2.hse.ie/conditions/rsv/
What is the RSV season?
The RSV season is a term used to describe the period when RSV is ‘circulating in the community’. In Ireland, RSV outbreaks typically occur in the autumn/ winter months with the highest numbers of infections usually reported in December and January every year. RSV usually circulates in the community in Ireland from September right through to end of February. The RSV immunisation programme from September to February would offer protection to the newborn cohort during the RSV season. The catch-up programme will ensure that all those most vulnerable to complications of RSV are immunised ahead of the take-off of infection rates and protected throughout that autumn/winter period.
What happens if a newborn baby is discharged home before being offered nirsevimab?
Nirsevimab is recommended for all newborn babies before they leave the maternity hospital. However, if for some reason a baby has not received nirsevimab before being discharged arrangements may be made for the baby to return to the hospital for immunisation. But both for protection of the baby and convenience of parents and guardians, as well as avoiding adding pressure to health services during very busy winter periods, immunisation prior to discharge is strongly advised.
Can nirsevimab cause RSV?
The nirsevimab injection does not contain RSV and cannot cause RSV or related illnesses.
What is the difference between nirsevimab and a vaccine?
Nirsevimab is an antibody that provides direct protection against RSV to the newborn baby (passive immunsiation). A vaccine stimulates the baby’s own immune system to mount an immune response, which includes making antibodies (active immunisation).
How will nirsevimab be given?
It is administered by intramuscular injection into the newborn baby’s thigh.
When is the best time to get immunised?
Nirsevimab can be given from birth and is recommended at the earliest opportunity to protect young babies in first days and weeks of life, when the risk of severe RSV infection is at its greatest, especially for babies born in winter. It will be given to the baby before they are discharged home from the maternity hospital.
For other infants in the catch-up cohort, immunisation can be given at HSE clinics which are running from the end of August to the beginning of October and booking can be made via the booking portal.
How quickly does nirsevimab start working?
It starts providing protection again RSV infection straight away.
Will babies need a top-up injection?
No. One injection of nirsevimab is sufficient to provide cover against RSV infection throughout the baby’s first winter.
Does nirsevimab provide lifelong protection against RSV infection?
No. It provides protection for the first 150 days, corresponding to the period the virus circulates and when babies are most at risk from RSV infection. As babies get older, the infection is much milder with a less severe illness.
Will nirsevimab interfere with the baby’s other immunisations?
No. Nirsevimab is a passive antibody immunisation. It does not require the baby to generate its own antibodies using the baby’s own immune system, nor does it interfere with the baby’s immune response to vaccines in the current immunisation schedule. Therefore, babies can begin the normal course of immunisations that start at two months of age.
Is nirsevimab safe?
Yes. The detailed scientific trials and its use in other countries have found it to be very safe. Side effects are mild and uncommon. The most common side effect is mild to moderate rash (0.7%) occurring within 14 days after the injection. Also, fever may occur in 0.6% and tenderness at injection site in 0.4% of babies within 7 days after the injection. Allergic reactions or hypersensitivity reactions have been rarely reported. Babies will be monitored after the injection and necessary treatment will be available if needed.
How effective is nirsevimab?
It is about 80% effective at avoiding serious complications and hospitalisations in immunised babies and infants, in international and Irish studies.
Where do I get information about nirsevimab?
Parents & guardians will be provided with an information leaflet. For babies receiving immunisations after birth, the midwife/nurse giving nirsevimab to the baby will provide information and available to answer any queries. For other infants receiving their immunisation in HSE clinics in the community, the healthcare team there can provide further information.
Do l have to pay for the nirsevimab immunisation?
The nirsevimab immunisation is provided free of charge to all eligible infants and babies through the HSE RSV Programme.
Will the HSE run the programme again in the winter 2026/2027?
A final decision on the nature of a future RSV immunisation and vaccination programme is awaited from the Department of Health which will inform the design and delivery of future HSE immunisation and vaccination services for RSV for adults and children.
Publication date: 8 August 2025