Real-World Effectiveness of Influenza Vaccination in Preventing Influenza and Influenza-Like Illness in Children

62/2025

Real-World Effectiveness of Influenza Vaccination in Preventing Influenza and Influenza-Like Illness in Children

Friday 10th October 2025

Rigamonti, V.; Torri, V.; Morris, S. K.; Ieva, F.; Giaquinto, C.; Donà, D.; Di Chiara, C.; Cantarutti, A.; CARICE study group

Background and objectives: Quadrivalent live attenuated influenza vaccines (LAIV-4) offer an alternative to inactivated influenza vaccines (IIV) for children aged 2–17 years, but data on their comparative effectiveness are limited. This study assessed vaccination rates and real-world effectiveness of LAIV-4 and IIV in preventing influenza and influenza-like illness (ILI) in Italian children during the 2022–2023 and 2023–2024 seasons. Methods: We conducted a population-based cohort study of children aged 2–14 years from September 2022 to April 2024, using data from Pedianet, a pediatric primary care database of anonymized records from family pediatricians. Children vaccinated with LAIV-4 or IIV were compared to unvaccinated children. The primary outcome was any first influenza or ILI episode. Monthly vaccination incidence rates per 1000 person-months were calculated for each vaccine type. Hazard ratios (HRs) and their 95 % confidence intervals (CIs) for vaccine effectiveness (VE) were estimated using adjusted mixed-effects Cox models. Results: A total of 65,545 (472,173 person-months) and 72,377 (527,348 person-months) children were included for the 2022–2023 and 2023–2024 seasons, respectively. Vaccination rates were 12.71 and 12.85 per 1000 person-months, respectively. Compared to unvaccinated children, LAIV-4 had an overall effectiveness of 43% (95% CI, 32%–53%), while IIV effectiveness was 54% (95% CI, 46%–61%). In 2022–2023, LAIV-4 (38% [95% CI, 12%–56%]) and IIV (49% [95% CI, 37%–58%]) had comparable effectiveness. In 2023–2024, LAIV-4 (40 % [95% CI, 25%–52%]) was slightly less effective than IIV (58% [95% CI, 44%–68%])(p = 0.048). Conclusions: An overall moderate, comparable effectiveness of LAIV-4 and IIV in preventing influenza/ILI among Italian children was observed.

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Rigamonti, V., Torri, V., Morris, S. K., Ieva, F., Giaquinto, C., Donà, D., ... & CARICE study group. (2025). Real-world effectiveness of influenza vaccination in preventing influenza and influenza-like illness in children. Vaccine, 53, 126946. https://doi.org/10.1016/j.vaccine.2025.126946