Exploring the drop in flu cases during the 2020-2021 season: The Italian case study

Purpose: To explore the 2020-2021 influenza season by describing the case of Italy.Methods: FluNet was searched for Italian data on virological samples. French, German, and Spanish data were collected for comparison. InfluNet was used for Italian epidemiological data on influenza-like illness (ILI). Data were extracted for the period from the 42nd week of 2020 to the 16th week of 2021 and for the previous 5-year period. The Containment and Health Index were used to describe the containment measures.Results: Among 6818 samples, 0% were positive in Italy in the 2020-2021 season (28.8% in the previous 5-year period; the percentage change in the total number of tested specimens was-51.3%). In France, Ger-many, and Spain, the percentage change was-23%,-7%, and-61%, respectively. The Italian ILI incidence remained below the baseline levels (mean 0.0144/10 0,0 0 0 inhabitants; range 0.0085-0.0204). In the pre-vious 5-year period, the mean incidence was 0.041/10 0,0 0 0 inhabitants. With the increase in containment measures, a deflection of ILI incidence was described ( P = .015).Conclusions: Despite the reduced number of collected specimens compared to previous seasons and a slight rise in influenza vaccination rates, containment measures represent the most likely factor that helped to reduce cases in the 2020-2021 influenza season in Italy.(c) 2022 Elsevier Inc. All rights reserved.