Higher Pediatric Influenza Vaccination Coverage in Pooled Northern Hemisphere Countries with Public Access to Live Attenuated Influenza Vaccine: Implications for Immunization Policy.

INTRODUCTION: Research shows that intranasal live attenuated influenza vaccine (LAIV) availability in addition to injectable inactivated influenza vaccine (IIV) is associated with higher influenza vaccination coverage rate (VCR). PEARL explored associations between LAIV availability and overall influenza vaccine uptake in children and adolescents. METHODS: PEARL was a cross-sectional study with ecological analysis using pooled country-level data from Northern Hemisphere countries with national recommendations for pediatric influenza vaccination (2024/25 season). Data sources included supra-national organizations and national public health institutes. LAIV availability was categorized as: none (IIV available); private (IIV available, LAIV accessible through the private market); or public (IIV available, LAIV offered via a publicly funded program). VCR was defined as the proportion of children and adolescents aged 2 to < 18 years receiving any influenza vaccine (LAIV/IIV) during the 2024/25 season. Beta regression assessed the association between LAIV availability and VCR, considering 27 covariates via two approaches: least absolute shrinkage and selection operator regression (Model 1); and literature-informed covariate selection (Model 2). Subanalyses assessed the association between LAIV availability (available versus none) and VCR, adjusting for vaccine funding structure (public: full, public: partial [funding restricted to specific age or high-risk groups], or private). RESULTS: Among 36 countries, 20 (55.6%) offered IIV and 16 (44.4%) offered LAIV and IIV. Median pediatric influenza VCR across all countries was 11.1%. VCR was higher in countries with publicly funded LAIV programs versus those offering only IIV in both analyses. In the subanalysis, the odds of influenza vaccination were higher in settings with public LAIV availability versus no LAIV availability (Model 1: odds ratio [OR] 2.66, 95% confidence interval [CI] 1.37-5.15; Model 2: OR 1.87, 95% CI 0.66-5.29). CONCLUSIONS: Higher pediatric influenza VCR was observed in settings with publicly funded access to LAIV. This positive association was directionally consistent regardless of vaccine funding structure.