Italian flu season 2020-2021: reasons for the drop and insights for the future

Background

Having seen the trend of 2020 flu season in the Southern hemisphere, the objectives of this study were to describe the trend of 2020-21 flu season in Italy, relating it with containment measures undertaken due to COVID-19, and to provide insights for next flu seasons and prevention of airborne diseases.

Methods

We collected data on Italian influenza virological samples on FluNet. We also collected French, German and Spanish data as a comparison. Data on Italian ILI (influenza-like illness) surveillance system were assessed with InfluNet. We used the Containment and Health Index of the Oxford COVID-19 Government Response Tracker (OxCGRT) to evaluate the impact of containment measures on Italian ILI incidence (Spearman's correlation).

Results

No sample out of 6818 tested positive to influenza virus in Italy in 2020-21 flu season; 21.6% of the samples tested positive to SARS-CoV-2. France, Germany and Spain registered a maximum of 0.10% of positive samples to influenza virus. In Italy the mean of positive samples to influenza virus in seasons from 2015-16 to 2019-20 was 28.8%; the mean number of processed samples in those seasons was 14008. ILI incidence in Italy remained at interseasonal levels during all flu season (mean 1.44/1000; range 0.85-2.04). According to the Containment and Health Index, with increasing containment measures a deflection of ILI incidence in Italy was described (p = 0.015).

Conclusions

Containment measures, along with rise of seasonal flu vaccination, are the most likely factors to explain the drop in cases in Italian 2020-21 flu season. The reduction of cases in neighbouring countries lower the role of the downsizing of Italian surveillance system seen in 2020-21 compared to seasons from 2015-16 to 2019-20. Rules and conducts may perpetrate the benefit on the decreased disease activity seen in 2020-21 flu season.

Key messages

Containment measures and flu vaccinations are the most impacting factors on the drop of influenza cases in 2020-21 in Italy.

Though the Italian surveillance system was downsized in 2020-21, the experience of neighbouring countries suggests that the decreased flu activity was factual.

[Selective pancreatic scintiscanning in the diagnosis of pancreatic diseases]

Pancreas scintiscanning using electronic image subtraction has proved useful in the diagnosis of pancreatic disease. Confirmation of this was found on comparison of the scintiscan picture and the surgical picture on gross inspection in 50 cases. Findings indicative of pancreatitis, cysts and tumours are illustrated, together with those given by scintiscanning of pancreas alterations occuring in the course of diseases affecting nearby organs.