Eurosurveillance - Volume 31, Issue 12, 26 March 2026

Community-acquired Legionnaires’ disease (LD) has increased globally, including Europe. Climatic exposures may contribute to this rise, yet evidence from high-incidence countries, such as Italy, is limited.

We aimed to assess LD seasonality at the national level and the effects of temperature, relative humidity and precipitation on LD incidence at the municipality level.

We analysed data on notified community-acquired LD cases and national climatic data from 2005 to 2023. Seasonality was assessed (peak-to-trough ratio (PTR)). A case time-series design with distributed lag nonlinear models was applied to estimate 1–10 week lagged effects of climatic exposures on LD incidence at the municipality level, as incidence rate ratios (IRRs).

Of the 28,662 notified LD cases, 27,458 (95.8%) were included. A clear seasonality was observed in the incidence, with a trough in early spring and a peak in autumn (PTR = 3.62; 95% confidence interval (CI): 2.45–5.34). Higher temperature and relative humidity had the strongest effects 10–9 weeks before disease onset (for 5°C increase above 15°C: IRR = 1.45; 95% CI: 1.33–1.58 and for 5% increase above 60%: IRR = 1.19; 95% CI: 1.12–1.26). Precipitation showed more immediate effects, particularly with a 1-week lag (for 5 mm increase above 10 mm: IRR = 1.07; 95% CI: 1.06–1.09). Findings were consistent among individuals aged ≥ 60 years.

A clear seasonal pattern was seen in the LD incidence, peaking in summer and autumn. Temperature and humidity increased LD risk over longer lags, while precipitation had shorter-term effects, suggesting climatic exposures influence environmental proliferation and immediate transmission of Legionella.

Vaccination of residents and healthcare workers (HCWs) against influenza in nursing homes is an important prevention strategy.

To describe trends in influenza vaccination coverage (VC) among HCWs working in nursing homes in France and measures implemented to support vaccination campaigns from 2007 to 2025, and to identify effectiveness of these measures.

We analysed data from seven nationwide cross-sectional studies conducted between seasons 2007/08 and 2024/25 and performed multivariate analysis using negative binomial regressions, to identify determinants.

National influenza VC among HCWs decreased from 37.2% (95% CI: 35.7–39.4) in 2007/08 to 24.2% (95% CI: 23.2–25.1) in 2024/25 (mean: 39,740 HCWs per season, 6 seasons). Vaccination coverage disparities by category of HCWs (2024/25 VC of physicians: 56.3%; nurses: 34.2%; nursing assistants: 19.3%) were observed throughout the period. Measures to promote influenza vaccination were less frequently implemented over time: support of vaccination campaigns by the management team (from 2018/19: 89% to 2024/25: 52%), implementation of collective (68% to 49%) or individual information sessions (19% to 9%), distribution of information on influenza vaccines (64% to 53%) or influenza (83% to 69%). Seven measures exhibited effectiveness in 2018/19 compared to only four in 2024/25, which had less effectiveness. Management teams highlighted the strong reluctance of HCWs to receive influenza vaccination.

Influenza VC among HCWs in nursing homes is marked by disparities among professional categories. To mitigate the decline in VC among HCWs, it is essential to implement effective measures to support the campaigns.