Summary
Each winter, around 2,000 whānau in Aotearoa New Zealand (NZ) have their lives affected by infant hospitalisation for respiratory syncytial virus (RSV) complications. RSV is the leading cause of lower respiratory tract infection (bronchiolitis) leading to hospitalisation in infants, with the greatest burden in the first months after birth. Māori and Pacific infants are disproportionately affected. Material hardship, household crowding, and cold, damp housing contribute to RSV prevalence and severity.
Effective immunisations against RSV are now available in the form of long-acting monoclonal antibodies (nirsevimab or clesrivomab) given to newborns and maternal RSV vaccination during pregnancy (RSVpreF (Abrysvo)). They are widely used internationally, creating an opportunity for NZ to significantly reduce hospitalisations, ease winter health system pressure, and improve equity. RSV immunisation represents a high‑impact and economically efficient strategy that justifies rapid policy approval and implementation in NZ.
RSV is a major public health and health system burden
RSV is the single most common cause of bronchiolitis (wheezy illness in infants) and viral pneumonia, and the leading driver of respiratory hospitalisations in early childhood.1 In Aotearoa New Zealand (NZ), around 1,800-2,000 children under 5 years are hospitalised with RSV each year.2 Around half of these hospitalisations occur in infants, particularly those under six months. This equates to an estimated 15-20 hospitalisations per 1000 infants each season, making RSV the leading cause of hospital admissions in the first year of life .2
RSV is highly seasonal in NZ with a pronounced annual winter peak, placing sustained pressure on primary care, emergency departments, paediatric hospital beds, and intensive care, as well as worry and upheaval for whānau.
The burden of RSV is not evenly distributed. Hospitalisations disproportionately affect Māori and Pacific infants, children from socioeconomically deprived households, and those living in crowded housing conditions.2
Beyond the immediate illness, there is increasing evidence that RSV infection in infancy is associated with recurrent preschool wheeze and asthma, further adding to the long-term burden on families and the health system.3
The economic costs are considerable. In Western Australia, the cost of a single infant RSV hospitalisation in 2023 has been estimated at AUD$12,000–13,700 per admission, with higher costs for infants requiring intensive care or prolonged hospital stays.4 Applied to NZ, hospital care of RSV alone would cost more than $25 million annually, before accounting for emergency department care, primary care visits, parental/carer time away from work, and potential longer‑term respiratory morbidity.
RSV prevention enters a new phase
Until recently, options to prevent RSV were limited. Over the past five years, NZ has funded the monoclonal antibody palivizumab (Synagis), given as a monthly injection during the RSV season to a small number of infants at highest risk of severe RSV disease, such as very preterm infants or those with severe heart defects at birth. This prophylaxis has helped protect a few hundred infants across the country each year. However, monthly palivizumab injections are costly, burdensome for whānau and healthcare staff, and cannot be delivered at scale. As a result, most babies hospitalised with RSV, who are usually born at term and were healthy, have had no protection against the virus.
Two additional RSV prevention strategies are now available and increasingly used internationally: direct infant immunisation with a long‑acting monoclonal antibody (nirsevimab or clesrivomab), and maternal RSV vaccination during pregnancy (RSVpreF (Abrysvo)). These options represent a leap forward in the ability to prevent RSV disease in infancy (see summary table).
Nirsevimab and clesrivomab both provide season-long protection with a single dose, so have effectively superseded Palivizumab which requires multiple injections over a single RSV season. Therefore, any ongoing RSV immunisation programme should ensure access to a long-acting RSV monoclonal antibody, at least for those at the highest risk of severe RSV disease.
Real-world studies from countries that have introduced nirsevimab indicate high effectiveness against hospitalisation, ranging from 70-90%.5-8 Maternal vaccination with RSVpreF (Abrysvo) is 70% effective at preventing severe RSV infection in infants up to 6 months.9 Reducing RSV disease in infancy would ease predictable winter pressures across all health services. For whānau, prevention of hospital stays means less time away from work caring for unwell infants, reduced disruption to family life, and improved long-term health for their children.
Table 1: Summary of RSV immunisation strategies for infants:
| | Infant immunisation: Nirsevimab or clesrivomab | Maternal vaccination: RSVpreF (Abrysvo) | Implications for NZ |
| Type of intervention | Long‑acting monoclonal antibody (not a vaccine) | Vaccine given during pregnancy | Licensure and funding required as part of National Immunisation programme (NIP) |
| How protection is provided | Infant receives ready‑made antibodies in one injection | Mother produces antibodies that pass to the baby before birth | High coverage needed for maximum population protection |
| Duration of protection | Entire RSV season with a single dose (up to 6 months protection) | Peak protection from birth to 5-6 months of age | As above |
| Target population | All infants, including preterm infants; & high-risk children entering their 2nd RSV season. | Infants born to vaccinated mothers | Nirsevimab or clesrivomab still needed for preterm infants and those missed by antenatal vaccination |
| Effectiveness | Substantial reduction in RSV‑related hospitalisation (70-90%) and up to 92% reduction in ICU admissions (6–8) | 70% effective at preventing severe RSV infection in infants up to 6 months (9) | Both strategies address the infant RSV burden |
| Delivery pathway | Ideally included in the National Immunisation Programme (NIP) to be given at birth or seasonally | Routine antenatal care, as with other vaccines in pregnancy (whooping cough and influenza vaccine) | Can leverage existing infrastructure but newborn monoclonal will require additional funding to integrate delivery into NIP |
| Equity considerations | Protects infants regardless of antenatal care access or gestational age | Depends on timing and uptake of antenatal care | Having both options help address inequities affecting Māori and Pacific infants |
| Relationship to palivizumab | Largely replacing palivizumab internationally as a universal infant or high-risk targeted strategy | Nirsevimab or clesrivomab may be combined with vaccine for highest-risk infants | Highest-risk infants will continue to need access to a monoclonal antibody (nirsevimab or clesrivomab) for RSV protection |
| Role in RSV strategy | Universal infant programmes have the strongest evidence for seasonal RSV prevention (6) | Complementary strategy to protect infants from birth and utilises existing maternal antenatal immunisation care pathways | Supports a coordinated national infant RSV prevention strategy, rather than piecemeal funding |
| Cost-effectiveness | Higher upfront cost, strong evidence of cost-effectiveness through prevention of hospitalisations & intensive care use | Lower cost, with cost-effectiveness driven by prevention of early hospitalisations | Awaiting decision on funding and delivery |
Why is NZ lagging on RSV prevention?
The World Health Organization recommends all countries introduce immunisation options for the prevention of severe RSV disease in young infants.10 Many comparable countries have moved rapidly to fund RSV immunisation and are reaping immediate benefits of reduced RSV infant hospitalisation.5-7,11 The United Kingdom, the United States, Chile, much of Europe, and Australia have now introduced long-acting infant RSV immunisation, maternal RSV vaccination, or both as part of their national immunisation programmes.
In contrast, NZ has yet to plan and fund a universal RSV immunisation strategy for infants. While nirsevimab has been highly ranked through PHARMAC prioritisation processes, progress has been slow, with Medsafe approval still pending a year after the application was submitted, and the maternal vaccine (Abrysvo) and clesrivomab only entering the Medsafe review process.
In NZ, vaccines are generally assessed and funded through the same regulatory pathways as other medicines and devices, with Medsafe determining licensure and PHARMAC independently making funding decisions. As a result, vaccines progress through the same assessment, cost-utility, and budget processes as other pharmaceuticals, even when their population-level benefits may be greater. Yet NZ has shown it can act quickly when immunisation is treated as a public health priority. The COVID-19 response in 2021 and meningococcal B program in 2000 are clear examples. RSV highlights the limitations of the current approach. It causes a substantial, predictable, and preventable burden of disease but has not prompted the same coordinated action.
What this Briefing adds
- The clinical, economic, and human burden from RSV disease is considerable. It is concentrated in early infancy and disproportionately affects Māori and Pacific families, and those living with economic hardship and material deprivation.
- The availability of effective infant immunisation (nirsevimab or clesrivomab) and maternal vaccination (RSVpreF (Abrysvo)) creates a clear opportunity to reduce avoidable winter illness, ease pressure on health services, and improve equity.
- Many comparable countries now fund new RSV prevention programmes because they are cost-effective. International experience indicates that RSV immunisation is most effective when integrated into a national immunisation program, rather than assessed and delivered as standalone intervention.
Implications for policy and practice
- RSV immunisation represents a high-impact and economically efficient strategy that justifies rapid policy approval and implementation through NZ’s national immunisation programme.
- As part of this programme, NZ needs to introduce long-acting monoclonal RSV antibody (nirsevimab or clesrivomab) to replace Palivizumab, which is being phased out.
- The mechanism NZ is using to assess new vaccines needs to be reviewed to avoid costly delays with approving and implementing needed and cost-effective vaccines.
Authors details
Dr Hazel C Dobinson, Paediatric Infectious Disease Specialist, Te Wao Nui Child Health, Wellington Hospital
Claire MacDonald, Midwifery Advisor, New Zealand College of Midwives.
Dr Jutta van den Boom, President of Perinatal Society of New Zealand, Neonatal Paediatrician, Waikato Hospital
Professor Catherine (Cass) Byrnes, Paediatric Respiratory Specialist, Waipapa Taumata Rau | University of Auckland.
Associate Professor Emma Best, Paediatric Infectious Disease Specialist, Immunisation Advisory Centre, Waipapa Taumata Rau | University of Auckland.
