HIQA’s rapid assessment of RSV immunisation strategies

Introduction: Respiratory syncytial virus (RSV) is a highly contagious virus that infects the lungs and upper airways. It is transmitted by coughing, sneezing and breathing. This virus spreads every winter, with the RSV season in Ireland typically running from October to March. In healthy individuals, infection with RSV is usually self-limiting; however, RSV can cause severe infections in some people, leading to hospitalisation. Groups vulnerable to serious complications include infants, young children and older adults.

In August 2024, the Health Information and Quality Authority (HIQA) published a rapid health technology assessment (HTA) to inform an interim Government policy decision on immunisation of infants and or older adults against RSV for the 2025-2026 season.

Specifically, we looked at the one-year costs for the Health Service Executive (HSE) of different immunisation strategies involving infants aged less than one year, and for adults aged 65 and older.

The request from the Department of Health followed a clinical recommendation from the National Immunisation Advisory Committee (NIAC) for the immunisation against RSV of all infants in their first RSV season and for adults aged 65 years or older.

In the meantime, the HSE has launched its RSV Immunisation Pathfinder Programme as a temporary measure for the current 2024-2025 season. The Pathfinder Programme applies to babies born between 1 September 2024 and 28 February 2025. Parents are encouraged to have their babies immunised free of charge before leaving the maternity unit.

Methodology

Our work on this rapid HTA began in January 2024 with support from a multidisciplinary expert advisory group. Given the timeline available, the assessment comprised a description of technology, a summary of international practice, a consideration of national and international epidemiology and the burden of disease, and a costing analysis.

Prevention and treatment

Strategies for the prevention of RSV in the general population typically focus on encouraging behaviours to limit virus transmission, such as reducing social contacts when an individual is symptomatic, and encouraging good hand and respiratory hygiene practices.

A number of forms of immunoprophylaxis are authorised in Europe that provide passive immunisation against RSV in children; since 2022, these now include options for infants in the general population. These include a long-acting antibody, nirsevimab (Beyfortus®), administered directly to the infant, and a maternal vaccine RSVpreF (Abrysvo®), administered to pregnant women, thereby providing infant protection through transplacental antibody transfer. At the time of our assessment, two vaccines had been authorised for the immunisation of adults aged 60 years and older: RSVPreF3 (Arexvy®), RSVpreF (Abrysvo®). Since then, a third vaccine (Respiratory Syncytial Virus mRNA vaccine (mRESVIA®)) has also been authorised.

Prior to the 2024-2025 RSV season, which saw the introduction of the HSE’s RSV Immunisation Pathfinder Programme, palivizumab (Synagis®) was provided by the HSE for infants and children up to two years of age who were considered to be at highest risk of severe disease caused by RSV. In two published recommendations in October 2023 and April 2024, NIAC recommended that nirsevimab should replace palivizumab for these infants and children. Since the start of the 2024-2025 RSV season, the current standard practice has changed and nirsevimab is now given to these infants in place of palivizumab.

Our review of international practice found that policy decisions have been informed by data from randomised controlled trials and emerging observational data from countries that implemented RSV immunisation for the 2023-2024 season. These data suggest that these technologies are safe and effective. Given the recent authorisation of nirsevimab and the RSV vaccines, we noted that international practice is changing rapidly.

Impact of RSV

The rapid HTA considered data from the Health Protection Surveillance Centre (HPSC) and the Hospital In-Patient Enquiry (HIPE) system.

HPSC data for period 2013 and 2023 indicated that among:

• those aged 0 to 4 years, approximately two thirds of notified cases, RSV-related emergency department attendances and hospital admissions occurred in infants aged less than one year, with a disproportionate number of admissions occurring in those aged less than six months.
• adults aged 65 years and older, burden typically increased with age, with on average almost half of notified cases, RSV-related emergency department attendances and hospital admissions reported in adults aged 80 years and older.

Hospital utilisation data from the HIPE system for the period 2013 to 2022 showed that there is a substantial burden associated with RSV in terms of hospitalisations and ICU admissions. While the annual burden has varied, the highest burden was consistently seen in those aged 0 to 4 years, with the majority of this burden seen in those aged less than one year, and occurring in quarter four (October to December) each year.

While testing capacity has increased, we noted that the identified data are likely an underestimate of the total burden, as not all RSV cases are laboratory confirmed and some discharges may not be coded.

Costing analysis findings

We undertook a costing analysis for a range of potential immunisation strategies for the 2025-2026 RSV season. Given assumptions around uptake, the cost of the products, administration costs and considering potential cost offsets due to hospitalisations averted:

• The estimated one-year cost to the HSE of immunising infants during their first RSV season ranged from ¤3.9 million to ¤19 million, depending on the approach taken. These costs would be partially offset by the fact that fewer infants would require hospital care.
• Offering an RSV vaccine to everyone aged 65 years and older was estimated to cost ¤146 million, while it would cost over ¤76 million if only offered to those aged 75 years and older. The potential for cost offsets in older adults was noted to be low as there are relatively few confirmed hospitalisations for RSV in this age group.

Moreover, we found that immunising children up to two years of age at increased risk of severe disease with nirsevimab instead of palivizumab would cost less than current care.

Our analysis found substantial uncertainty in relation to these one-year costs, and that these estimated one-year total costs were highly dependent on assuming a favourable product unit cost for the interventions.

In addition to the costs of the various strategies, we identified that there would be implementation costs (for example, IT system updates, information and training) which would likely apply with the introduction of any new RSV programme irrespective of the included target population(s) and or immunisation uptake.

We highlighted that there would be substantial organisational challenges associated with extending RSV immunisation to the general infant and or older adult population, given the large number of individuals involved and the aim to maximise uptake within a short time frame before the start of the RSV season. Specifically, this considered the potential to offer immunisation to approximately 28,000 infants born outside of the RSV season and up to 840,000 adults aged 65 years and older in primary care settings. Furthermore, given the uncertainty in relation to the cost associated with the different RSV strategies, we advised that product cost should be a key consideration in any decision-making.

Additionally, we advised that data collection will be important to support ongoing monitoring and evaluation of the effectiveness of any programme that is implemented. A public information campaign would also be essential to raise awareness and support informed decision-making.

What’s next?

Our assessment was submitted as advice to the Minister for Health and the HSE to inform an interim policy decision on the most appropriate RSV immunisation strategy for the 2025-2026 RSV season.

We are now conducting a full HTA to provide advice to inform a longer-term government policy decision about RSV immunisation — that is, 2026 and beyond — which we will publish later this year. It will include emerging international evidence as well as experience from the HSE’s current RSV Immunisation Pathfinder Programme.

For more information:

• HIQA’s rapid HTA of immunisation against RSV is available at www.hiqa.ie.
• Information from the HSE on RSV is available at www2.hse.ie/conditions/rsv/.
• Information on the HSE’s RSV Immunisation Pathfinder Programme is available at www.gov.ie/.

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Read the HPN Jan/Feb 2025