Uptake and predictors of newborn respiratory syncytial virus (RSV) immunisation with nirsevimab in Ireland’s national pilot programme: a cross-sectional study

Objectives: To assess uptake of nirsevimab, a long-acting monoclonal antibody for respiratory syncytial virus (RSV) prevention, during the first season of Ireland’s Pathfinder pilot universal newborn immunisation programme and to identify socio-demographic and perinatal predictors of uptake. Design: Cross-sectional analysis of routinely collected programme data. Setting: Ireland’s Mid-West region, served by University Maternity Hospital Limerick, the sole maternity and neonatal hospital for the region. Participants: Infants born 1 September 2024 to 28 February 2025. Outcome measure: Uptake of nirsevimab before hospital discharge. Results: Overall uptake was 89.4% (1600/1790) and did not vary by month (p=0.119); it was similar by sex (male 89.5%, female 89.2%; p=0.838). Preterm infants had higher uptake than term (96.9% vs 88.7%; p=0.001), and those admitted to the neonatal unit also had higher uptake (93.0% vs 88.4%; p=0.009). In adjusted analyses, maternal age (adjusted OR (aOR) 1.06 per year, 95% CI 1.03 to 1.09, p<0.001) and preterm birth (aOR 3.08 (95% CI 1.14 to 8.37), p=0.027) were associated with uptake. Uptake varied by maternal ethnicity: 91.5% in white Irish, 53.6% in Irish Traveller (aOR 0.13 (95% CI 0.08 to 0.23)), 79.7% in other white background (aOR 0.39 (95% CI 0.24 to 0.61)), 90.0% in black or black Irish, 98.3% in Asian or Asian Irish and 84.2% in other/mixed or prefer not to say. Although uptake among white Irish was high, they accounted for the largest absolute number of infants who did not receive nirsevimab, reflecting their predominance in the birth cohort. Conclusions: During the first season of Ireland’s Pathfinder RSV pilot programme in the Mid-West region, nearly 90% of newborns received nirsevimab before discharge. Uptake was consistently high across months, indicating effective implementation but lower among infants of Irish Traveller and other white background mothers, highlighting the need for targeted, culturally adaptable equity strategies within a high-uptake programme. These findings may inform national and international policies and offer practical lessons for universal RSV immunisation.