Live Attenuated Influenza Vaccine (LAIV) for Children for the Prevention of Influenza Illness in Sweden: A Cost-Effectiveness Analysis.

INTRODUCTION Both inactivated influenza vaccine and live attenuated influenza vaccine (LAIV) (indicated for use in children aged 2-17 years) effectively prevent influenza transmission and related outcomes. Despite high transmission among children, vaccination practices in Sweden focus primarily on targeting individuals at higher risk of influenza-related illness and mortality, including older adults. The objective of this study was to assess the cost-effectiveness of increasing LAIV coverage among children aged 2-17 years.

Methods

We developed a de novo health economic model (HEM) that included a dynamic transmission model (DTM) component to estimate population-level outcomes for a typical influenza season in Sweden. The DTM implemented a compartmental structure to model the prevalence of three influenza strains over a 1-year time horizon. The HEM used a decision-tree structure to translate epidemiological outputs into clinical and economic outcomes. The model simulated theoretical vaccination scenarios, comparing a reference scenario based on historical vaccination coverage with an intervention with LAIV in which coverage among children aged 2-17 years was increased from 0.36% to 25%.

Results

Increasing the uptake of LAIV in 2-17-year-olds could prevent a further 505,824 influenza infections in a typical season, two-thirds of which would be prevented in the indirect population (adults and children aged < 2 years). The model estimated this to translate into 33,419 fewer cases requiring medical attention, of which 1929 were hospitalizations, ultimately preventing 193 intensive care unit admissions and 99 deaths. The intervention scenario was considered cost-effective from a payer perspective (direct costs only; incremental cost-effectiveness ratio of SEK 73,266 per quality-adjusted life year) and dominant (cost-saving) from a societal perspective. Sensitivity and scenario analyses showed that results were robust to changes in key model parameters, maintaining cost-effectiveness.

Conclusions

In Sweden, the implementation of LAIV is estimated to be cost-effective in 2-17-year-olds by reducing disease burden and healthcare costs in both children and the broader population.