Criteria for RSV Prophylaxis

Information for Families

Respiratory syncytial virus, RSV, is one of the viruses that causes bronchiolitis and is predominantly seen from October to February each year. Most children get it and are ok, but many do get admitted, especially if they have an underlying serious medical condition or were born very prematurely or have lung disease.

After infancy, it does not cause such big issues, more like a cough and cold, but not bronchiolitis, which is mainly something in the first year of life, maybe up to 18 months or so.

We have criteria based on extensive evidence, as they are worldwide studies. They have produced yearly criteria for which children should receive immunoglobulin therapy to try and prevent them catching RSV during their first winter.

Clinics run across hospital sites by a neonatal sister or a community sister. Infants who are identified as needing RSV prophylaxis will be contacted to come in for these clinics, usually starting from October of that year. Assistance from Principal Pharmacist W&C, Royal Free London, Bleep 1412, Ext 36443.

It is usually given to babies with Down Syndrome who have a significant heart abnormality, meaning they have a significant right-to-left shunt (ie blood going the wrong way/shunting) and are usually on medications too. Other reasons could be, for example, on respiratory grounds in a baby with chronic lung disease or an ongoing daily oxygen requirement. It is rarely given after the first year.

See this parent leaflet: Why is my baby being offered an RSV immunisation?

Further Research and Information

In the "green book", immunisation guidance can be found here: Respiratory syncytial virus.

Please note this advice changes yearly and needs updating and checking each year.

Some research indicates that all children with DS should have RSV immunisation due to their increased risk of bronchiolitis/LRTI, hospital admissions and morbidity, accompanied by this, even without congenital heart disease or chronic lung disease. However, at the time of writing (September 2026) this is not universal for all infants with Down Syndrome and is only offered to those who are identified as high-risk for all the reasons outlined below in Box 1.

Palivizumab for children with Down Syndrome: is the time right for a universal recommendation? Archives of Disease in Childhood Published Online First: 27 December 2018.

Palivizumab passive immunisation against Respiratory Syncytial Virus (RSV) in at-risk pre-term infants.

This clearly needs further local and national evaluation and discussion with Public Health England.

More Information on the Respiratory Syncytial Virus (RSV)

Respiratory syncytial virus (RSV) is a common cause of respiratory tract infections. It usually causes a mild self-limiting respiratory infection in adults and children, but it can be severe in infants and older adults who are at increased risk of acute lower respiratory tract infection (LRTI; sometimes termed lower respiratory tract disease, LRTD), including bronchiolitis in infants. RSV bronchiolitis is an important cause of emergency department attendances and amongst the leading causes of infant hospital admissions.

RSV is readily transmissible. The incubation period is considered to range from two to eight days and infectious period from three to eight days. The virus is spread from respiratory secretions through close contact with infected persons via respiratory droplets or contact with contaminated surfaces or objects. RSV infections occur year-round but primarily within the period October to February, and with most infections occurring in a relatively short epidemic of about six weeks.

Those infected by RSV experience a range of acute respiratory infection (ARI) symptoms such as rhinitis, cough, shortness of breath, wheeze, lethargy and sometimes fever. RSV LRTI can include pneumonia in all ages, and bronchiolitis in young children, in whom it may also cause decreased oral intake. RSV also causes croup and otitis media in children.

Predisposing clinical risk factors for severe RSV disease amongst infants include congenital heart disease, chronic lung disease, chromosomal abnormalities, neuromuscular disorders, large airway abnormalities, and immunodeficiency. Prematurity is similarly an important risk factor for admission in infancy.

RSV Vaccines

At time of writing there are no approved RSV vaccines for infants; such an approach is unlikely to provide protection during the most vulnerable first months of life due to the immaturity of the immune system. Vaccine development for older infants requires clinical trials to determine efficacy and safety, including assurances around the possible risk of vaccine-associated enhanced respiratory disease.

Infant RSV Protection

Infant RSV protection is therefore through passive immunity, either by vaccination of the pregnant mother for transplacental passive immunisation of the baby in-utero or by direct administration to the infant of a monoclonal antibody.

Recommendations for the Use of RSV Immunisations

The objective of the RSV immunisation programme is to lower the incidence and severity of RSV LRTI in:

• older people as part of the routine immunisation programme.
• infants through maternal vaccination as part of the routine immunisation programme.
• very and extremely preterm infants (born before 32 weeks gestation) through selective immunisation.
• infants and young children at high risk of severe RSV disease through selective immunisation.

For a universal programme for infant protection, JCVI (Joint Committee on Vaccination and Immunisation) has advised (June 2023) maternal vaccination with Pfizer pre-F vaccine (Abrysvo®) or infant immunisation with nirsevimab (Beyfortus®) would be suitable for a national programme. JCVI subsequently advised that clesrovimab (Enflonsia™) be considered equally suitable for universal infant immunisation (October 2025). JCVI has advised that high risk infants and young children receive either nirsevimab (February 2023 advice) or clesrovimab (October 2025 advice), or palivizumab if neither first line monoclonal antibody immunisation is available. JCVI has advised (2024 and 2025) that in a universal programme of maternal vaccination, clesrovimab or nirsevimab immunisation should be considered for very and extremely preterm infants (born before 32 weeks), who are unlikely to benefit from maternal vaccination, to be offered in or immediately preceding their first RSV season.

Selective Immunisation of Very and Extremely Preterm Infants

To reduce the risk of severe disease, infants born very or extremely prematurely (less than 32 weeks) are recommended to receive a dose of a long-acting monoclonal antibody, clesrovimab (Enflonsia™) or nirsevimab (Beyfortus®), during or preceding their first RSV season. Choice of long-acting monoclonal antibody may depend on local and national NHS arrangements. Typically infants being discharged from hospital for the first time between mid-September and the end of February should be immunised with clesrovimab or nirsevimab while an inpatient. Those leaving hospital for the first time from the start of March to first half of September should be invited for outpatient immunisation scheduled in the second half of September or first half of October. Health service operational guidance should be followed.

Selective Immunisations for High Risk Infants and Young Children

To reduce the risk of severe disease, eligible high-risk infants and young children are recommended to receive RSV monoclonal antibody immunisation seasonally. This should be offered regardless of whether the mother was vaccinated during the pregnancy.

• Clesrovimab (Enflonsia™) or nirsevimab (Beyfortus®) are the recommended first-line immunisations, if available. Choice of long-acting monoclonal antibody may depend on local and national NHS arrangements.
• Palivizumab (Synagis®) is recommended if neither of the first line products is available.

Typically infants being discharged from hospital for the first time between mid-September and the end of February should be immunised with clesrovimab or nirsevimab while an inpatient. Those leaving hospital for the first time from the start of March to first half of September should be invited for outpatient immunisation scheduled in the second half of September or first half of October. Health service operational guidance should be followed.

All children in the following high-risk groups (Box 1) are recommended to receive an RSV monoclonal antibody immunisation.

Infants are defined as children less than 12 months old; this is chronological age since birth and not prematurity-corrected/adjusted age.

Only a single dose of clesrovimab or nirsevimab is required for protection in a season.

Box 1

High risk due to chronic lung disease of prematurity (CLD), also known as bronchopulmonary dysplasia (BPD).

Pre-term infants who have moderate or severe CLD. Moderate or severe CLD is defined as preterm infants with compatible x-ray changes who continue to receive supplemental oxygen or respiratory support at 36 weeks post-menstrual age.

Children who remain in oxygen at the start of the RSV season are also considered to be at higher risk.

These infants may include those with conditions including:

• pulmonary hypoplasia due to congenital diaphragmatic hernia.
• other congenital lung abnormalities (sometimes also involving congenital heart disease or lung malformation).
• interstitial lung disease and including those receiving long term ventilation (LTV) at the onset of the season.

High risk due to Congenital Heart Disease (CHD).

Preterm infants with haemodynamically significant, acyanotic CHD at the chronological ages at the start of the RSV season and gestational ages at birth.

Infants (children less than 12 months of age) with cyanotic or acyanotic CHD plus significant co-morbidities particularly if multiple organ systems are involved.

High risk due to Severe Combined Immunodeficiency Syndrome (SCID).

Children less than 24 months of age with SCID, the most severe form of inherited deficiency of immunity, who are unable to mount either T-cell responses or produce antibody against infectious agents, until immune reconstituted.

Where clinical judgement of other individual patient circumstances strongly suggests that prophylaxis would prevent serious RSV infection in infants who are at particular risk of complications from RSV, use of clesrovimab or nirsevimab (first-line, if available) or palivizumab could be considered during the RSV season.

Contraindications

There are very few individuals who cannot receive an indicated RSV vaccine or immunisation. Where there is doubt, appropriate advice should be sought from a specialist or the local immunisation team.

Other Immunisations

Infant monoclonal antibody immunisation: RSV monoclonal antibodies can be given at the same time or around the same as any vaccines scheduled to be administered as part of the routine childhood immunisation programme.

References

JCVI minutes

• Joint Committee on Vaccination and Immunisation (2026). Minutes of the meeting held on 4 February 2026. Available from gov.uk.
• Joint Committee on Vaccination and Immunisation (2024). Minute of the meeting held on 02 October 2024. Available from gov.uk.
• Joint Committee on Vaccination and Immunisation (2023). RSV immunisation programme: JCVI advice, 7 June 2023. Available from gov.uk.

Journal papers

• Wilson M, Whitaker H, Walker J, et al. (2026) Maternal RSV vaccination and reduced risk of hospitalisation for babies in England, 2024/25. ESCMID. European Society of Clinical Microbiology and Infectious Disease. khub.net.
• Hogan AB, Mitchell A, Stadler E, et al. (2026) Quantifying the association between neutralising antibodies and protection from RSV disease in infants and adults: A systematic review and meta-analysis. medRxiv: 2026.02.13.26346212. doi: 10.64898/2026.02.13.26346212.
• Zar HJ, Simões EAF, Madhi SA, et al. (2025a) Clesrovimab for Prevention of RSV Disease in Healthy Infants. New England Journal of Medicine 393(13): 1292-303. doi: 10.1056/NEJMoa2502984.
• Zar HJ, Bont LJ, Manzoni P, et al. (2025b) Clesrovimab in Infants and Children at Increased Risk for Severe RSV Disease. New England Journal of Medicine 393(13): 1343-45. doi: 10.1056/NEJMc2506107.
• Hodgson D, Wilkins N, van Leeuwen E, et al. (2024) Protecting infants against RSV disease: an impact and cost-effectiveness comparison of long-acting monoclonal antibodies and maternal vaccination. Lancet Reg Health Eur. 2024 Jan 8;38:100829. doi: 10.1016/j.lanepe.2023.100829.
• Drysdale SB, Cathie K, Flamein F, HARMONIE Study Group et al. (2023). Nirsevimab for prevention of hospitalization due to RSV in infants. N Engl J Med. 2023 Dec 28;389(26):2425-2435.
• Domachowske J, Madhi SA, Simões EAF, MEDLEY Study Group et al. (2022) Safety of nirsevimab for RSV in infants with heart or lung disease or prematurity. N Engl J Med 386.9: 892-894.
• Hammitt LL, Dagan R, Yuan Y, MELODY Study Group, et al. (2022) Nirsevimab for Prevention of RSV in Healthy Late-Preterm and Term Infants. N Engl J Med. 2022;386(9):837-846. doi: 10.1056/NEJMoa2110275.