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. 2025 Apr 19:53:126946.
doi: 10.1016/j.vaccine.2025.126946. Epub 2025 Feb 28.

Real-world effectiveness of influenza vaccination in preventing influenza and influenza-like illness in children

Vera Rigamonti  1 , Vittorio Torri  2 , Shaun K Morris  3 , Francesca Ieva  4 , Carlo Giaquinto  5 , Daniele Donà  6 , Costanza Di Chiara  7 , Anna Cantarutti  8 ; CARICE study group
Affiliations
Free article

Real-world effectiveness of influenza vaccination in preventing influenza and influenza-like illness in children

Vera Rigamonti et al. Vaccine. .
Free article

Abstract

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.

Keywords: Children; Influenza; Influenza vaccine; Population-based study; Real-world data; Vaccine effectiveness.

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Conflict of interest statement

Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

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